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§ · tools

Free tools for operators. No signup.

A growing library of client-side tools for founders, operators, and growth teams. Calculators, generators, checkers, builders, and branded PDF document templates. Every tool runs entirely in your browser. Nothing is saved, shared, or sent to a server.

§ 01 · the workbench

A quiet tray of operator tools.

We built these for our own team first, then for the operators we work with. They load fast, run in the browser, and stop asking for your email after the third use, because they never asked in the first place. Calculators that tell you the truth about unit economics. Generators that ship valid markup against the schema.org SoftwareApplication spec. Checkers that give you a verdict, not a homework list.

in short
  • 109 free in-browser tools across ecommerce, SEO, business documents, brand, content, and marketing.
  • Every tool runs entirely client-side; no signup, no email, no data leaves the tab you opened.
  • Covers SEO schema, ecommerce profit math, Shopify ROI, business naming, content readability.
  • Built on real public specs — schema.org, web.dev, MDN Web APIs — not vendor-locked dashboards.
  • Free editorial alternatives to paid SaaS tools like SEMrush, Ahrefs, or Clearscope — bookmark-grade, not trial-grade.
298
free tools
$0
ever cost
0
signup fields
100%
browser only
most-used this week
Editorial operator's workbench flat-lay showing all Digital Heroes tools arranged as hand-drawn labeled cards on cream paper, moss-green ink, single amber accent
Fig. 01 · the workbench · 145 tools, one cream tray
§ 02 · filter & search
business · generatornew

Quote Generator

Build a priced quote with line items, tax, discount, notes. Export as a DH-branded PDF. Presets for agency, consultant, service work.

line items branded PDF validity window
Open tool
business · generatornew

Receipt Generator

Log a payment with payer, method, amount, balance, and item detail. Branded PDF. Presets for service, rent, partial payment.

payment log IRS-ready rent receipts
Open tool
business · generatornew

Purchase Order

Issue a buyer-side PO with ship-to, bill-to, terms, and line items. Branded PDF. Presets for services, goods, software subscription.

buyer-side NET-30 terms ship + bill
Open tool
business · generatornew

SOW Generator

Multi-page statement of work with scope, deliverables, acceptance criteria, milestones. Branded PDF. Consulting, software, creative presets.

5-page PDF acceptance milestones
Open tool
brand · generatornew

Business Name Generator

Fifty candidate brand names across five naming styles: abstract, evocative, compound, founder, descriptive. Industry-tuned word lists.

5 styles 50 names 9 industries
Open tool
brand · generatornew

Slogan Generator

Forty taglines across five brand tones: confident, warm, minimal, bold, clever. Keyword-driven from your brand, noun, value, audience.

5 tones 40 taglines tone-aware
Open tool
content · checkernew

Readability Checker

Five readability scores: Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, SMOG, ARI. Flags long sentences. Target grade 8 for web.

5 scores sentence flags grade level
Open tool
content · checkernew

Headline Analyzer

Score any blog title, meta title, or ad headline 0-100 on length, power words, emotion, format fit, and SERP-pixel width.

score 0-100 SERP pixels 4 contexts
Open tool
content · checkernew

Character Counter

Live counts of characters, words, sentences, paragraphs, lines, and reading time. Plus colored threshold badges for tweet (280), Bluesky (300), SEO title (60), meta description (155), Google Ads.

6 thresholds unicode-aware top words
Open tool
dev · formatternew

JSON Formatter

Validate, pretty-print, minify, sort keys, escape, unescape. Parse errors with exact line + column. Browser-only — your JSON never leaves the page, safe for API responses with secrets.

validate + pretty sort keys line+col errors
Open tool
design · generatornew

Lorem Ipsum Generator

Words, sentences, or paragraphs in four variants — classic Cicero Latin, hipster, designer-jargon, plain English. The placeholder text every wireframe needs without the cookie-walled generator pages.

4 variants words/sent/para HTML wrap
Open tool
dev · converternew

Case Converter

Type once, see all 12 cases live: UPPERCASE, lowercase, Title, Sentence, camelCase, PascalCase, snake_case, CONSTANT_CASE, kebab-case, dot.case, aLtErNaTiNg, iNVERSE. Click any to copy.

12 cases live click to copy smart split
Open tool
dev · converternew

Markdown → HTML

Type Markdown left, see live HTML preview right, raw HTML below. GitHub-flavored mode (tables, task lists, autolinks). Copy or download as a complete .html file. Powered by marked.js (MIT).

GFM toggle live preview .html download
Open tool
dev · encodingnew

Base64 Encoder / Decoder

Auto-detect direction, URL-safe mode (RFC 4648 §5) for JWTs and URL params, file upload for binary, optional MIME detection + data:URI prefix wrap. UTF-8 native, browser-only.

URL-safe mode file upload data:URI
Open tool
dev · validatornew

JSON Validator

Deeper than parse-pass-fail. Surfaces parse errors with line + col + 30-char context. Common-mistake detector (BOMs, trailing commas, single quotes, comments). NDJSON / JSON Lines mode validates each line.

NDJSON mode 6-mistake detector structure stats
Open tool
dev · encodingnew

URL Encoder / Decoder

Auto-detect direction. Three modes: encodeURIComponent (per-param), encodeURI (full URL), form (space-as-plus). Built-in query-string parser breaks URLs into key / value pairs.

3 encode modes query parser RFC 3986
Open tool
content · converternew

Title Case Converter

Type once, see all eight renderings: AP Stylebook, Chicago Manual, MLA, APA 7th, NYT, sentence case, every-word-capped, ALL CAPS. Each card explains its style-guide rule. Click to copy.

8 styles live acronym-safe click to copy
Open tool
content · generatornew

URL Slug Generator

Transliterates accents (NFD), strips reserved characters, optional stopword removal, max-length truncation at word boundary. Hyphen / underscore separator, change log shows what was modified.

accent-safe word-boundary trim change log
Open tool
dev · testernew

Regex Tester

JavaScript RegExp flavor. Live highlight of every match, capture groups + named groups in side panel, replace preview with $1/$2 references, all 6 flags, library of 8 common patterns (email, URL, phone, ISO date, IPv4, UUID, hex, slug).

live highlight capture groups 8 presets
Open tool
content · calculatornew

Reading Time Calculator

Live word count plus four reading-speed bands (slow / average / fast / scan) per Brysbaert 2019 baseline. Content-type multipliers for technical, narrative, casual prose. Custom WPM override.

4 speed bands content-aware 238 wpm default
Open tool
dev · converternew

CSV → JSON Converter

Two-way CSV ↔ JSON with auto-detected delimiter (comma / tab / semicolon / pipe), header row, and type inference. JSON array or NDJSON output. File upload supported. 100% in-browser, works offline.

auto-delimiter NDJSON output file upload
Open tool
dev · converternew

HTML → Markdown

Live side-by-side preview. GFM extension (tables, task lists, strikethrough). Bullet style and code-block style toggles. Copy or download as .md. Reverse direction of our Markdown → HTML. Powered by Turndown (MIT).

GFM tables live preview .md download
Open tool
dev · validatornew

YAML Validator

Live syntax check, parse-error line + col with surrounding context, equivalent JSON view to verify type inference, common-mistake detector for tabs / mixed indent / Norway-problem booleans. Powered by js-yaml (MIT).

JSON view multi-doc 6-mistake check
Open tool
design · generatornew

CSS Gradient Generator

Linear, radial, conic gradients with unlimited color stops and draggable positions. Live preview, CSS output, Tailwind config snippet for design-system tokens. 6 brand-themed presets included.

3 gradient types unlimited stops Tailwind snippet
Open tool
design · buildernew

Box Shadow Generator

Stack up to 5 shadow layers — per-layer offset, blur, spread, color, alpha, inset. Material elevation 1-4, neumorphism, soft-glow, retro hard, brutalist presets. Live preview on adjustable background.

5-layer stack 8 presets Material elevation
Open tool
design · optimizernew

SVG Optimizer

Strips comments, editor metadata (Inkscape, Adobe, Sketch), redundant default attributes. Rounds decimals to configurable precision. Side-by-side preview + byte-savings percentage. Each pass independently toggleable.

6 cleanup passes live preview savings %
Open tool
design · extractornew

Color Palette Extractor

Drop image to extract dominant + 8-color palette via median-cut quantization. Hex, RGB, HSL output per swatch. Click to copy. Tailwind config + CSS variables export. Powered by ColorThief (MIT).

median-cut algo 8 swatches Tailwind export
Open tool
design · calculatornew

Image Compression Calculator

Batch image compressor: drop many files at once, live quality slider, JPG / WebP / AVIF / PNG output, optional max-width downscale, per-file savings %, one-click ZIP export. Pure canvas API, no upload.

9 variants JPEG/WebP/AVIF resize toggle
Open tool
cro · calculatornew

A/B Test Sample Size

Per-variation sample size from baseline conversion + minimum detectable effect + power + confidence. Time-to-significance projection from daily traffic. Two-proportion z-test math.

z-test math time projection scenarios
Open tool
finance · calculatornew

Startup Runway Calculator

Cash on hand + monthly burn + optional revenue → runway in months + extinction date + Chart.js visualization across four burn scenarios (current, +10% creep, -10% easy cuts, -25% restructure).

4 scenarios Chart.js timeline stage presets
Open tool
cro · calculatornew

Statistical Significance

Post-test analysis. Control + variant visitors and conversions in; p-value, confidence, lift, and verdict at 90/95/99% threshold out. Two-tailed default with one-tailed toggle.

p-value 4 verdict states technical breakdown
Open tool
saas · calculatornew

SaaS LTV:CAC Ratio

ARPU + gross margin + churn + CAC → LTV, LTV:CAC ratio, CAC payback. Industry-standard verdict bands at 1, 3, 5 cuts. Contribution-margin LTV (not the inflated revenue version).

4 verdict bands CAC payback stage presets
Open tool
saas · calculatornew

SaaS Magic Number

Sales-efficiency ratio per Scale VP definition. Previous-quarter S&M + current-quarter Net New ARR → magic number with five verdict bands (poor / monitor / healthy / under-investing / scale).

5 verdict bands canonical formula board-deck ready
Open tool
saas · calculatornew

SaaS Quick Ratio

(New MRR + Expansion) divided by (Churned + Contraction). The Mamoon Hamid growth-efficiency ratio with stage-aware verdict (Seed / Series A / B / C / Growth) showing whether the business is compounding or treading water.

5 stages 2 engines + 2 leaks stage benchmark
Open tool
saas · calculatornew

Burn Multiple Calculator

Net cash burn divided by net new ARR. The David Sacks 2020 framework with verdict tiers (amazing under 1, great 1-1.5, good 1.5-2, OK 2-3, suspect over 3). Cash-runway sanity check included.

Sacks tiers runway sanity $/$ growth
Open tool
saas · calculatornew

DAU/MAU Ratio Calculator

Stickiness percentage from daily active over monthly active. 7 category benchmarks (messaging, social, productivity, B2B daily/weekly, content, ecommerce). Habit-tier classifier per the Andrew Chen 20% line.

7 categories engaged-MAU habit tiers
Open tool
saas · calculatornew

Cohort Retention Calculator

24-month survivor curve from monthly retention rate, plus cohort half-life and total revenue per cohort. 5 category presets (B2B SaaS, consumer SaaS, mobile app, DTC subscription, marketplace). Chart.js retention curve.

24-mo curve half-life 5 categories
Open tool
ecommerce · calculatornew

Break-Even ROAS Calculator

Minimum ROAS to break even on ad spend = 1 / contribution margin. Refund-adjusted floor + LTV-aware target + operating multiple. Honest paid economics that account for COGS, refunds, and repeat purchases.

3 ROAS thresholds refund-aware LTV-aware
Open tool
dev · checkernew

HTTP Headers Checker

Paste raw response headers from curl -I or DevTools. Audits caching, security (HSTS, CSP, X-Frame, Referrer-Policy, Permissions-Policy), compression, server fingerprint. Letter-grade verdict.

A-F grade 5 categories paste mode
Open tool
dev · detectornew

CMS Detector

Paste HTML source — we identify 25+ platforms (WordPress, Shopify, Squarespace, Wix, Webflow, Ghost, Magento, BigCommerce, Hugo, Next.js, Gatsby, Astro, etc.) with weighted-confidence scoring per match.

25+ platforms confidence score evidence trail
Open tool
dev · detectornew

Tech Stack Detector

Paste HTML — scans 60+ tools across 10 categories: JS/CSS framework, analytics (GA, Plausible, Mixpanel, PostHog), payment (Stripe, PayPal), ads (FB Pixel, TikTok), chat (Intercom, Crisp), A/B testing.

60+ tools 10 categories signature evidence
Open tool
dev · parsernew

User Agent Parser

Paste any UA string — get browser + version, OS + version, rendering engine, device class. Bot detection covers ~25 crawlers including AI training bots (GPTBot, ClaudeBot, Google-Extended, PerplexityBot).

25 bot signatures AI crawler aware my-UA preset
Open tool
dev · detectornew

Web Server Detector

Paste Server header / response headers — identifies origin (nginx, Apache, IIS, Caddy), CDN / edge (Cloudflare, Vercel, Netlify, Fastly, CloudFront), app stack (PHP, ASP.NET, Express). Version-exposure security verdict.

15+ servers CDN + WAF detect security verdict
Open tool
dev · checkernew

HTTP Status Code Checker

Enter URLs — live-fetches each through AllOrigins. Reports status code, redirect chain, response time, plus per-code SEO verdict (301 vs 302 link-equity, 4xx categories, 5xx severity). Bulk URL paste supported.

live fetch redirect chain SEO verdict
Open tool
dev · checkernew

CORS Checker

Enter a target URL — runs live cross-origin GET, POST, and preflight tests from your browser. The browser's CORS error itself is the answer. Reports each Access-Control-* response header with a recommendation per failure mode.

live test preflight aware per-error fix
Open tool
dev · checkernew

Cookie Analyzer

Paste Set-Cookie headers OR read this page's live cookies. Audits Secure, HttpOnly, SameSite (Lax / Strict / None), Path, Domain, Max-Age vs Expires, __Host- + __Secure- prefixes. OWASP-aligned hardening verdict.

paste or live RFC 6265bis OWASP audit
Open tool
dev · checkernew

CSP Validator

Paste Content-Security-Policy header — parses every directive, flags unsafe-inline, unsafe-eval, wildcards, missing critical directives (default-src, script-src, frame-ancestors). Letter-grade hardening audit, OWASP-aligned.

A-F grade per-directive CSP Level 3
Open tool
dev · detectornew

JavaScript Framework Detector

Paste HTML — identifies the JS framework (React, Vue, Angular, Svelte, Solid, Preact, Lit, Alpine, htmx) plus deeper layers: meta-framework, state management, routing, data fetching, UI library, build tool. Full developer-experience picture.

9 frameworks 7 tooling layers deep signature
Open tool
dev · detectornew

CDN Detector

Paste curl -I or DevTools headers — identifies Cloudflare, Fastly, CloudFront, Vercel, Netlify, Akamai, Bunny, KeyCDN by signature header (cf-ray, x-vercel-id, x-served-by, x-amz-cf-id, +15 more). Multi-CDN stack detection.

20+ CDNs multi-CDN aware per-CDN advice
Open tool
dev · checkernew

Compression Detector

Paste curl -I — checks Content-Encoding (gzip / brotli / deflate / zstd / none), validates Vary: Accept-Encoding correctness, recommends optimal compression by traffic profile. RFC 9110-aligned.

5 algorithms Vary check Brotli + Zstd
Open tool
dev · checkernew

Cache Headers Checker

Paste curl -I — parses Cache-Control directives (max-age, s-maxage, public, private, no-cache, no-store, immutable, stale-while-revalidate), validates ETag + Last-Modified pairing. A-F caching grade per RFC 9111.

A-F grade RFC 9111 9 directives
Open tool
dev · checkernew

HTTP/2 + HTTP/3 Checker

Paste curl -I — identifies HTTP protocol version (1.1 / 2 / 3) from status line, validates Alt-Svc header for HTTP/3 advertising, recommends upgrade path. RFC 9113 / RFC 9114-aligned.

Protocol version Alt-Svc parse QUIC-aware
Open tool
dev · checkernew

Redirect Chain Checker

Paste curl -ILv output — traces every 301 / 302 / 307 / 308 hop with destination URL, flags chain length, mixed 301/302 (link-equity bug), and protocol/host downgrades. Loop detection.

hop trace 301/302 audit loop detect
Open tool
dev · checkernew

IP Geolocation Lookup

Live IP-to-place lookup via ipapi.co free public API. Country, region, city, ISP, ASN, timezone, currency, calling code. Works for any IPv4 / IPv6 — or detects your own.

live API IPv4 + IPv6 ASN / ISP
Open tool
dev · checkernew

Mobile-Friendly Test

Live Google PSI mobile audit — checks viewport, tap targets ≥48×48, font size ≥12px, content-width fit. Pass/fail per audit + fix recommendation. Critical for mobile-first indexing (Oct 2023).

PSI live 4 audits SEO-ranking signal
Open tool
dev · checkernew

HTTPS / SSL Checker

Composite TLS posture: live HTTPS reach + crt.sh Certificate Transparency log (cert history + issuer) + Cloudflare DoH CAA records (issuer authorization). A-F TLS-posture grade.

A-F grade crt.sh CT log CAA + reach
Open tool
dev · checkernew

Domain Authority Checker

Composite 0-100 site-maturity score from public APIs: Wayback age + crt.sh cert count + CAA + SPF + DMARC. Honest about being NOT Moz DA — links out for paid backlink intel.

5 signals honest framing A-F grade
Open tool
dev · checkernew

Site Health Checker

PSI 4-category composite (Performance 40% + SEO 25% + Best Practices 20% + Accessibility 15%) with weighted health grade + top 5 cross-category fixes ranked by impact. Mobile or desktop strategy.

4-cat composite top 5 fixes A-F grade
Open tool
dev · checkernew

Page Weight Analyzer

PSI resource-summary breakdown — bytes by HTML / CSS / JS / image / font / third-party with per-type budget verdict. Surfaces the budget gap that's leaking weight.

7 types per-type budget A-F grade
Open tool
dev · checkernew

Render Blocking Checker

PSI render-blocking-resources audit — every CSS / JS file blocking initial paint with byte size + estimated LCP savings + per-file fix (critical CSS / async / defer / lazy-load).

LCP savings per-file fix CSS + JS
Open tool
dev · checkernew

JavaScript Size Checker

PSI per-bundle JS breakdown — every JS file with size, first-party vs third-party split, top 10 by size, parse + execute time estimate on mid-tier mobile.

1P / 3P split parse-time est. top 10 files
Open tool
dev · checkernew

Multi-URL Audit

Bulk PSI audit on up to 5 URLs sequentially — comparison table with Performance / SEO / Accessibility / Best Practices scores + worst audit per URL flagged. Copy-table export.

5 URLs side-by-side copy export
Open tool
dev · checkernew

CSS Size Checker

PSI per-stylesheet breakdown — every CSS file with byte size, first-party vs third-party split, render-blocking flag. PurgeCSS guidance + Google Fonts audit.

1P/3P split RB flag A-F grade
Open tool
dev · checkernew

External Link Counter

Paste HTML — splits internal vs external <a> tags, lists rel attributes (nofollow, sponsored, ugc, noopener), flags missing rel=noopener security on target=_blank links.

int/ext split rel audit noopener check
Open tool
dev · checkernew

Heading Hierarchy Checker

Paste HTML — parses H1-H6 outline tree, flags multiple H1s, skipped levels, missing H1, empty headings. WCAG 2.4.6 + SEO featured-snippet ready.

outline tree skip detect WCAG 2.4.6
Open tool
dev · checkernew

Image Format Checker

Paste HTML — scans every <img> for format (JPG / PNG / WebP / AVIF / SVG / GIF), loading=lazy, srcset, width+height (CLS prevention). Modern-format adoption %.

6 formats CLS check lazy + srcset
Open tool
dev · detectornew

Hosting Provider Detector

DoH + ASN composite — identifies AWS, GCP, Azure, Vercel, Netlify, Cloudflare, DigitalOcean, Hetzner, Linode, OVH, Shopify, WP Engine + 15 more by ASN classification.

25+ hosts ASN classify tier verdict
Open tool
dev · checkernew

Backlink Signal Checker

Live backlink verifier — paste up to 10 candidate URLs + your domain, fetches each, confirms link is present with anchor + rel + dofollow status. Honest about NOT being Ahrefs / Moz.

live verify honest framing 10 URL batch
Open tool
ecommerce · calculator

Profit Calculator

Contribution margin, net profit, and margin percentage from revenue minus COGS, shipping, fees, ads, and fixed costs.

contribution net margin verdict
Open tool
ecommerce · calculator

Shopify ROI Calculator

Payback month, 12-month return, and 3-year cumulative value on a Shopify rebuild from current GMV and lift assumptions.

payback 3-year NPV lift model
Open tool
ecommerce · calculator

Blended CAC Calculator

True customer-acquisition cost past vendor dashboards. Sum paid + organic + tools + fees; divide by new customer count.

blended CAC MER paid share
Open tool
ecommerce · calculator

LTV Calculator

Gross LTV, contribution LTV, LTV:CAC ratio, and CAC payback months from AOV, frequency, lifespan, and margin.

gross LTV LTV:CAC payback
Open tool
ecommerce · calculatordepth

CAC Payback Period

Exact months to recover acquisition cost. Cohort-aware retention curve, gross-margin adjustment, risk verdict per bracket.

months to payback cohort curve
Open tool
ecommerce · calculator

ROAS Calculator

Return-on-ad-spend per channel, blended ROAS, and break-even ROAS from gross margin. Honest channel-level math.

per-channel break-even blended
Open tool
ecommerce · calculatornew

AOV Calculator

Average order value, CM per order, and category benchmark. Interactive lift simulator: what each +$5 of AOV adds in revenue.

lift simulator 8 categories CM/order
Open tool
ecommerce · calculatornew

Break-Even Calculator

Break-even units, revenue, CM per unit, margin of safety, and days-to-break-even at your daily order velocity.

BEP units margin of safety days runway
Open tool
ecommerce · calculatornew

Markup Calculator

Bidirectional: enter cost plus markup %, margin %, or selling price. Markup vs margin conversion table, category presets, effective margin with shipping + CAC.

bidirectional conversion table effective margin
Open tool
seo · generatornew

Schema Markup Generator

Valid JSON-LD for Article, Product, FAQPage, LocalBusiness, Event, BreadcrumbList. Real-time validation, copy-ready, spec-aligned.

JSON-LD 6 types validated
Open tool
seo · generatornew

Article Schema Generator

Dedicated Article / BlogPosting / NewsArticle generator. Auto-counts headline at 110 chars, validates author + datePublished + image dimensions, outputs ImageObject (not bare URL).

3 sub-types 110-char gate ImageObject
Open tool
seo · generatornew

Product Schema Generator

Product + Offer + AggregateRating + Brand. Includes the merchant-listing fields (priceValidUntil, shippingDetails, hasMerchantReturnPolicy) Google requires for shopping rich results.

merchant-grade offer + rating return policy
Open tool
seo · generatornew

LocalBusiness Schema Generator

PostalAddress + GeoCoordinates with 5-decimal precision + per-day OpeningHoursSpecification. 14+ LocalBusiness subtypes (Restaurant, Dentist, Plumber, etc.). NAP-consistency reminder.

14 sub-types geo + hours NAP-aware
Open tool
seo · generatornew

Review Schema Generator

Switch between individual Review and aggregate AggregateRating. Pick itemReviewed type from 10 options (Product, LocalBusiness, Movie, Book, Recipe, etc.). Self-serving check baked in.

2 modes 10 itemReviewed policy gate
Open tool
seo · generatornew

FAQ Schema Generator

Add unlimited Q+A pairs, get FAQPage JSON-LD with required fields. Inline validator catches duplicates, empty answers, and 220-char question over-length. Visible-mirror policy explained.

unlimited Q+A dup-check policy gate
Open tool
seo · generatornew

Breadcrumb Schema Generator

Build BreadcrumbList JSON-LD with auto-numbered ListItem positions. Live SERP-style preview. The one rich result Google still renders for commercial sites in 2026.

auto-numbered SERP preview CTR +3-7pp
Open tool
seo · generatornew

Event Schema Generator

Date + venue + offers + organizer. Includes the post-pandemic eventAttendanceMode + eventStatus fields Google requires (Offline / Online / Mixed). 11 Event subtypes.

11 sub-types attendance mode ticket offers
Open tool
seo · generatornew

Meta Tag Generator

Title, description, OG, Twitter Card with live Google SERP, Facebook, and X previews. Stack presets for HTML, WordPress, Shopify, Next.js Metadata API.

3 previews 4 stacks char counter
Open tool
seo · checkernew

Open Graph Preview

Side-by-side preview of Facebook, X, LinkedIn, Slack, and Discord share cards. Paste HTML to auto-extract tags. Quality score 0-100, image dimension check.

5 platforms quality score HTML parser
Open tool
seo · checkernew

Canonical URL Checker

Paste page HTML — extracts the rel=canonical link, validates absolute / HTTPS / non-duplicate / no fragment / no UTM params. Catches the 'two canonical tags' bug.

5 checks duplicate detect paste-HTML
Open tool
seo · checkernew

Hreflang Checker

Paste HTML — extracts every rel=alternate hreflang tag, validates ISO 639-1 + ISO 3166-1 codes against full lookup table, x-default presence, en-UK typo trap.

ISO validation x-default check UK→GB warn
Open tool
seo · checkernew

Twitter Card Validator

Paste HTML — extracts twitter:card / title / description / image / site / creator. Validates lengths + HTTPS image. Falls back to OG tags exactly like X's parser.

4 card types OG fallback paste-HTML
Open tool
seo · checkernew

Internal Link Counter

Paste HTML + your origin. Splits every <a> into internal / external / fragment / pseudo-URL. Lists unique destinations + flags accidental nofollow on internal links.

4 categories ≥3 floor nofollow detect
Open tool
seo · checkernew

Anchor Text Analyzer

Paste HTML + brand + target keyword. Buckets anchors as branded / URL / generic / partial / exact-match. Live ratio bars with the 8% exact-match safe-ceiling threshold.

5 buckets ratio bars scheme gate
Open tool
dns · checkernew

MX Record Checker

Type a domain — queries Cloudflare DoH for MX records, lists each by priority, and resolves each mail-server hostname's A record so you see the full delivery chain.

priority sort A-resolve DoH
Open tool
dns · checkernew

SPF DKIM DMARC Checker

Email-auth triple-lock check. SPF mechanism count (10-lookup limit), DMARC policy strictness + pct=, DKIM with selector input. Required by Gmail+Yahoo since Feb 2024.

3 records SPF lookup count policy gate
Open tool
dns · checkernew

CNAME Lookup

Walks every CNAME hop until it reaches a terminal A or AAAA record. Catches alias loops + missing terminals. Flags chains over 2 hops (latency cost).

chain follow loop detect ≤ 2 hops
Open tool
dns · checkernew

DNS Propagation Checker

Queries Cloudflare 1.1.1.1 + Google 8.8.8.8 in parallel. Match = propagated globally. Mismatch = still propagating across resolver caches. 6 record types supported.

2 resolvers parallel query match-check
Open tool
dns · checkernew

IP Lookup

Type a hostname or IP. Resolves A + AAAA, performs reverse DNS (PTR), and surfaces the hosting provider hint (AWS / GCP / Azure / Vercel / Cloudflare) from the PTR string.

A + AAAA + PTR 10 providers IP-input mode
Open tool
domain · checkernew

Domain Availability Checker

Type a domain — one RDAP query tells you whether the registry has a record. No registrar funnel, no email gate, no affiliate redirect. Five reputable registrar links rendered for open names.

RDAP gateway acquisition signals no affiliate
Open tool
ssl · checkernew

SSL Certificate Inspector

Pulls the most-recent cert from public Certificate Transparency logs via crt.sh: issuer, subject, full SAN list, validity dates, days remaining. No agent install, no TLS handshake from your IP.

CT logs SAN list 5 quality checks
Open tool
ssl · bulknew

SSL Expiry Monitor

Paste up to 20 hostnames at once. We query CT logs for each and render a sorted dashboard — days remaining, issuer, status band. Most cert outages live on a sub-domain you forgot you had.

20 hosts at once 3 status bands copy summary
Open tool
recon · passivenew

Subdomain Finder

Enumerates every sub-domain ever issued a public SSL cert via Certificate Transparency logs. Passive — no scan packets at the target. Filter, sort, and CSV export the list.

CT enumeration live filter CSV export
Open tool
domain · historynew

Domain Age Checker

Cross-references RDAP registration date with Wayback Machine first-capture. Catches re-registered domains where the registry record looks fresh but the brand has been around for years.

RDAP + Wayback divergence flag re-registration
Open tool
marketing · buildernew

UTM Link Builder

Tag URLs with UTM parameters. 7 platform presets (Meta, Google, TikTok, LinkedIn, Email, Klaviyo, Newsletter), auto-lowercase, QR code output, localStorage saved campaigns.

7 presets QR code saved campaigns
Open tool
seo · generatornew

Robots.txt Generator

Platform presets for Shopify, WordPress, Webflow, Next.js. Individual toggles for every AI crawler (GPTBot, ClaudeBot, PerplexityBot, 12 more). Verdict line included.

15 AI bots 5 presets verdict
Open tool
seo · generator

XML Sitemap Generator

Paste URLs or upload CSV, set priority + changefreq + lastmod. Image and hreflang annotations supported. Auto-splits above 50,000 URLs into a sitemap-index.

auto-split 50k image sitemap hreflang
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seo · generator

Hreflang Generator

Three-format output (HTML tags, XML sitemap, HTTP headers) with built-in reciprocal-link validator that flags every missing pair in amber. 4 locale presets.

3 formats reciprocal check x-default
Open tool
seo · checker

Keyword Density Checker

1-gram, 2-gram, 3-gram density with stop-word filtering. Flesch reading ease bundled. Calibrated over-optimization thresholds per content type (blog / landing / product).

n-gram Flesch score threshold
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ecommerce · checkernew

Shopify Speed Test

Google PageSpeed data for all four Lighthouse categories. CrUX field data. Shopify-specific app weight table (Klaviyo, Yotpo, Judge.me, etc.) sorted by kilobytes.

app weight CrUX field
Open tool
business · generatornew

Invoice Generator

Client-ready PDF in 30 seconds. Four tax presets: US sales tax, UK/EU VAT with reverse-charge, India GST with CGST+SGST or IGST split, agency retainer. Multi-currency.

GST split VAT reverse PDF
Open tool
seo · flagship auditflagship

Website Audit

Four-category scorecard across Performance, SEO, Accessibility, and Best Practices. Runs Google PageSpeed Insights; surfaces top 2-3 wins per category with DH service pairing.

4 categories PSI API top wins
Open tool
seo · checkernew

Lighthouse Score Checker

Single-purpose Lighthouse scoring across Performance, SEO, Accessibility, Best Practices. Mobile + desktop strategy. Top 10 audit findings ranked by impact, radar chart visualization.

PSI API radar chart findings ranked
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seo · checkernew

Core Web Vitals Checker

28-day p75 field data from CrUX plus a lab run for LCP, INP, CLS, FCP, TTFB on any URL. Per-metric verdict tied to Google's published thresholds. Field-vs-lab comparison chart.

field + lab 5 metrics CrUX p75
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seo · checkernew

Domain Health Checker

Five-signal composite: DNS records, HTTPS reachability, domain age (RDAP + Wayback), first-archive timestamp, PageSpeed score. Single composite Health Grade A-F with breakdown bars.

5 signals DoH + RDAP grade A-F
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seo · checkernew

WHOIS Lookup

Live RDAP record for any domain: registrar, registration date, expiration, name servers, status flags. Dates auto-aged, status flags explained in plain language.

RDAP 6 cards EPP status
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seo · checkernew

DNS Lookup

A / AAAA / MX / TXT / NS / CNAME / CAA in one parallel query via Cloudflare DoH. SPF + DMARC auto-detected and badged. Hygiene verdict on email + SSL posture.

7 record types DoH SPF/DMARC
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seo · checkernew

Wayback Archive Viewer

First-capture date plus year-by-year snapshot timeline from Internet Archive. Click any year to open the snapshot. Coverage verdict per archive density.

timeline archive.org trust signal
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seo · checkernew

Structured Data Validator

Paste JSON-LD; we walk every node (including @graph), check ~30 rules per type across 8 schema.org types, surface pass/warn/fail per check. Runs entirely in your browser.

8 types @graph in-browser
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seo · checkernew

Robots.txt Tester

RFC 9309 longest-match in-browser. Paste robots.txt + URL(s); pick from 16 user agents (Googlebot, GPTBot, ClaudeBot, PerplexityBot, etc.). Bulk-test up to 50 URLs.

RFC 9309 16 UAs bulk URLs
Open tool
seo · generatornew

SERP Preview Generator

See your title, URL, and meta description rendered as a live Google search-result snippet — mobile + desktop side by side. Pixel-width gauges, query bold-match preview, truncation marked.

mobile + desktop pixel gauge live render
Open tool
seo · checkernew

Title Tag Checker

Eight checks per title: length, pixel-width vs Google's 580-px cut-off, brand placement, keyword position, capitalization, separator consistency, duplicates, stop-word density. Paste plain text or full HTML.

8 checks canvas pixel-width stop-words
Open tool
seo · checkernew

Meta Description Checker

Seven meta-description checks: length, mobile pixel-width, action-verb presence, primary-keyword position, sentence count, trailing punctuation, generic-CTA detection.

120-155 chars CTA detector 920px gauge
Open tool
seo · checkernew

Image Alt Text Checker

Paste HTML; we walk every <img> tag and run six checks per image: alt presence, decorative-empty, filename-as-alt, keyword stuffing, length, clickable-but-empty conflict. WCAG 1.1.1 alignment.

WCAG 1.1.1 DOM scan 6 checks/img
Open tool
seo · checkernew

XML Sitemap Validator

Paste a sitemap.xml; we run the full sitemaps.org spec: namespace, <loc> required, ISO-8601 lastmod, valid changefreq enum, 0.0-1.0 priority, 50K URL limit, same-origin rule. Handles sitemap-index too.

12 checks DOMParser urlset + index
Open tool
seo · checkernew

Color Contrast Checker

WCAG AA and AAA ratio for normal text, large text, and UI components. Live swatch preview, brand presets, verdict per threshold. Accessibility compliance first.

WCAG AA/AAA 5 thresholds swatch
Open tool
brand · generatornew

Favicon Generator

Upload one square image. Download a ZIP with 6 PNG sizes (16-512px), apple-touch-icon, web manifest, and copy-ready HTML head tags. Canvas-based resize.

6 sizes manifest ZIP download
Open tool
ecommerce · calculatornew

Conversion Rate Calculator

CVR percent, revenue per visitor, category benchmark, and incremental-revenue lift simulator from +0.5% to +2.0% CVR. DTC, beauty, fashion, B2B, SaaS presets.

CVR + RPV 6 categories lift slider
Open tool
ecommerce · calculatornew

Bounce Rate Calculator

Bounce percentage, engaged sessions, conversion impact, and category benchmark gap (DTC, blog, B2B, SaaS, lead-gen). Drop simulator shows incremental conversions from 5-20pp bounce reduction.

5 categories GA4-aware drop simulator
Open tool
ecommerce · calculatornew

Conversion Funnel Calculator

5-stage funnel: top-of-funnel volume × per-stage CVR. Identifies the leakiest stage by gap-vs-benchmark, projects incremental conversions from a +5pp lift on that stage. DTC, SaaS, B2B presets.

5 stages leak detect 3 templates
Open tool
ecommerce · calculatornew

CTR Calculator

Click-through rate, CPC spend, channel benchmark gap (Google Search, Meta, Display, TikTok, LinkedIn, email, organic SERP positions 1-10). Lift chart shows incremental clicks at +0.25 to +2pp.

9 channels organic positions lift chart
Open tool
ecommerce · calculatornew

Email List Growth Calculator

Net monthly subscriber growth from signup % minus churn %. Projects subscribers at 6/12/24 months as a chart, plots target line, computes monthly email revenue at horizon. Klaviyo, Mailchimp, Beehiiv presets.

24-mo projection target line $ at horizon
Open tool
ecommerce · calculatornew

Affiliate Commission Calculator

Per-sale commission, monthly + annual net (network-fee adjusted), tier-bonus targets, and recurring SaaS lifetime value per signup. Flat, tiered, and recurring models. DTC, course, SaaS, hosting presets.

3 models tier targets net of fees
Open tool
saas · calculatornew

Churn Rate Calculator

Logo churn, revenue churn, Net Revenue Retention, and annualized churn from monthly movement. SMB, mid-market, and enterprise SaaS presets with benchmark verdicts.

logo + revenue NRR annualized
Open tool
saas · calculatornew

MRR / ARR Calculator

End-of-month MRR, annualized ARR, net new MRR, MoM growth, and SaaS Quick Ratio from plan-mix movement. Early, growth, and scale-stage presets with Quick Ratio verdict.

Net New MRR Quick Ratio MoM growth
Open tool
marketing · buildernew

Shopify Discount URL

Auto-apply discount share URL with 5 redirect presets (home, product, collection, cart, checkout), optional UTM tags, and QR code download for offline campaigns.

auto-apply 5 redirects QR code
Open tool
seo · checkernew

Heading Outliner

Paste HTML, get an indented H1-H6 outline with warnings for missing H1, skipped levels, duplicate H1s, and empty headings. SEO and WCAG 1.3.1 compliance in one view.

H1-H6 tree skip warnings WCAG 1.3.1
Open tool
prompt · brandnew

Logo Prompt Generator

Build a structured, copy-paste logo prompt for Midjourney, Nano Banana, or DALL-E from your brand, industry, mood, and style inputs.

midjourneynano banana
Open tool
prompt · contentnew

Website Hero Prompt Generator

Generate a v0.dev or Claude Design prompt for a converting website hero section, tuned to your offer, audience, and visual direction.

v0.devclaude design
Open tool
prompt · contentnew

Landing Page Prompt Book

A structured prompt for full landing pages in Tailwind via v0.dev or Claude Artifacts: hero, sections, proof, FAQ, and CTA logic.

tailwindv0.dev
Open tool
prompt · ecommercenew

Product Photo Prompt Style

Compose a Nano Banana or Midjourney prompt for studio-grade product photography: lighting, surface, lens, and mood per SKU.

nano bananamidjourney
Open tool
prompt · marketingnew

Ad Creative Prompt

Generate a visual-hook prompt for paid-ad creative in Midjourney or Pencil, structured around the offer, angle, and scroll-stopper.

midjourneypaid ads
Open tool
prompt · marketingnew

Email Design Prompt

Build a prompt for Klaviyo / Postscript email + cart-flow design via Claude, structured around campaign goal, brand, and layout.

klaviyoclaude
Open tool
prompt · marketingnew

Social Post Prompt Generator

Generate a ChatGPT or Claude prompt for on-brand social posts, tuned to platform, audience, voice, and the post's job.

chatgptclaude
Open tool
prompt · brandnew

Brand Voice Prompt Rules

Turn your brand attributes into a reusable voice-and-tone system prompt for ChatGPT or Claude, so every output sounds like you.

chatgptclaude
Open tool
prompt · brandnew

App Icon Prompt

Compose a Midjourney or Nano Banana prompt for a polished app icon plus App Store presentation, from concept to grid-safe mark.

midjourneyapp store
Open tool
prompt · brandnew

Packaging Design Prompt

Generate a Midjourney prompt for product packaging concepts: format, material, finish, and shelf-presence direction per product.

midjourneypackaging
Open tool
§ 03 · the complete library

Every tool. One searchable index.

The full Digital Heroes tool library: the curated operator tools above plus the HeroTools suite of browser-local utilities — image, PDF, text & code, generators, SEO, productivity, and media. Every tool runs 100% on your device: no upload, no signup, and the HeroTools pages keep working offline once loaded. On any tool page, press Ctrl/⌘ K to search the whole library.

tools shown
AI Prompt Studio Build pro prompts for images, video & business copy — paste into Midjourney, Sora, ChatGPT. Avatar Generator Make initials avatars & identicons from any name or text — export PNG/SVG. Barcode Generator Generate Code 128 & EAN-13 barcodes and download as PNG or SVG. Bingo Card Generator Make custom bingo cards from your own word list — multiple unique cards, print-ready. Bulk QR Generator Generate hundreds of QR codes from a list or CSV — labeled and downloadable as a ZIP. Certificate Generator Create printable certificates — templates, recipient names, dates & signatures, PNG/PDF export. Color Converter Convert colors between HEX, RGB, HSL, HSV & CMYK with a live swatch. Color Palette Generator Generate harmonious color palettes — lock, tweak, copy & export CSS. Spacebar to reroll. CSS Generator Box-shadow, gradient, radius & glassmorphism CSS with live preview. Digital Business Card Generate a vCard QR people can scan to save your contact. Email Signature Maker Design an HTML email signature with live preview — paste into Gmail/Outlook. Emoji Picker Search 1,800+ emoji by name or category and copy instantly — with recents. Mock Data Generator Generate realistic fake names, emails & rows — export CSV/JSON. Password Generator Strong, random passwords & passphrases with a strength meter. Password Strength Tester Check how strong a password is — entropy, crack-time estimate & tips. Never sent anywhere. Privacy Policy Generator Generate a privacy policy & terms template for your website or app — answer a few questions, export HTML/Markdown. QR Code Generator Make QR codes for links, text, Wi-Fi & more — custom colors + logo. QR Code Scanner Scan QR codes with your camera or from an image — decoded locally. Signature Generator Draw or type your signature and download a transparent PNG — for documents & email. Test Card Number Generator Generate Luhn-valid test card numbers, CVV & expiry for QA/testing — not real cards. Avatar / Circle Cropper Crop any photo to a perfect circle or square avatar and export PNG. Background Remover Erase image backgrounds automatically with on-device AI — free (one-time engine download). Bulk Watermark Stamp text or a logo across many images at once. Collage Maker Combine photos into a clean grid collage with spacing — export PNG. Color Blindness Simulator See how an image looks with protanopia, deuteranopia, tritanopia & more. Design Studio Canva-style design tool — social-size presets, templates, text, shapes & snap guides. Design & export in your browser. EXIF Viewer & Remover See and strip hidden photo metadata (GPS, camera, date) — privately. Favicon Generator Turn any image into a full favicon & app-icon pack (.zip). HEIC to JPG Converter Convert iPhone HEIC/HEIF photos to JPG or PNG — batch, private, no upload. Image Annotator Mark up screenshots with arrows, boxes, text, blur & numbered steps — export PNG. Image Color Picker Pick colors and extract a palette from any image. Image Compare Slider Before/after slider to compare two images side by side — export the comparison. Image Compressor Shrink JPG, PNG & WebP with a live quality slider — no upload. Image Converter Convert between PNG, JPG, WebP & more, right in the browser. Image Cropper Crop, rotate & flip with aspect-ratio presets. Image Redactor Blur, pixelate or black-out sensitive parts of an image before sharing — locally. Image Resizer Resize by pixels, percent or presets — single or batch. Image Splitter / Grid Slice an image into an N×N grid (Instagram grid, tiles) — download as a ZIP. Image to ASCII Art Turn any image into ASCII art — copy as text or export as PNG. Image to Base64 Convert images to Base64 data URIs (with HTML/CSS/Markdown) and back — locally. Image to Text (OCR) Extract text from images & screenshots in your browser (one-time engine download). Image Upscaler Enlarge images 2×–4× with high-quality resampling & smart sharpening — fully on-device. Meme Generator Add classic top/bottom captions to any image and export. Passport Photo Maker Crop photos to passport & visa sizes (2×2", 35×45mm & more) with guides — print-ready sheets. Photo Border & Frame Add borders, padding, rounded corners & polaroid frames to photos — export PNG. Photo Editor A full layer-based photo editor — layers, blend modes, filters, brushes, text & transforms. Like Photoshop, in your browser. Photo Filters Apply filters & adjustments (B&W, vintage, contrast…) and download. Pixel Art Maker Draw pixel art on a grid — palettes, mirror mode, fill & export PNG at any scale. Placeholder Image Generate sized placeholder images with custom color & label — PNG or SVG. Screenshot Beautifier Drop a screenshot onto a gradient backdrop with padding, rounded corners & shadow — export PNG. SVG → PNG Rasterize SVG to crisp PNG at any scale, right in your browser. Text to Handwriting Convert typed text into realistic handwritten pages — paper styles, ink colors, PNG & PDF export. Word Cloud Generator Turn text into a word-frequency cloud and export PNG/SVG — runs in your browser. Audio Trimmer & Editor Import or record audio, trim, fade & adjust volume on a waveform — export WAV. GIF Maker Turn a set of images into an animated GIF — set delay, loop & size, export locally. Guitar Tuner Tune guitar, ukulele & bass with live microphone pitch detection — standard & custom tunings. Metronome A precise metronome with tap tempo, time signatures, accents & subdivisions. Mic & Webcam Test Test your microphone, webcam & speakers before calls — levels, preview & devices. Screen Recorder Record your screen (and mic) to a video file — locally. Speech to Text Dictate and get live transcription in your browser — many languages, copy & download. Subtitle Editor (SRT/VTT) Edit subtitles, shift & stretch timestamps, fix sync and convert SRT ↔ VTT — locally. Text to Speech Turn text into speech with your system voices. Video Compressor Shrink video file size with quality & resolution presets — in your browser (one-time engine download). Video Editor & Screen Recorder Camtasia-style studio — record your screen, webcam & voiceover, edit on a multi-track timeline with callouts, and export. No upload. Video to MP3 / Audio Extract MP3/WAV audio from a video, or convert audio formats — in your browser (one-time engine download). Video Trim & GIF Trim a video or turn it into a GIF — in your browser (one-time engine download). Voice Recorder Record audio from your mic and download it. Webcam Photo Booth Snap photos from your webcam with filters, countdown & mirror — download locally. White Noise & Ambience White, pink & brown noise plus rain and fan ambiences with a sleep timer — generated locally. YouTube Thumbnail Downloader Grab any YouTube video’s thumbnail in every resolution — just paste the link. Compress PDF Shrink PDF file size by recompressing pages & images — locally, no upload. Extract Images from PDF Pull all embedded images out of a PDF and download them (ZIP) — locally. Images → PDF Turn photos & scans into a single PDF. PDF → Images Render PDF pages to PNG/JPG at any resolution. PDF Editor Sejda-style PDF editor — click existing text to edit it (size & font matched), add text, images, shapes, whiteout & signatures. No upload. PDF Merge Combine PDFs and reorder pages by drag — locally. PDF Sign Draw or type a signature and place it on any page. PDF Split & Organize Extract, delete, rotate & reorder PDF pages. PDF to Text Extract selectable text from a PDF — by page, copy or download .txt, no upload. PDF Watermark & Page Numbers Add text watermarks and page numbers to a PDF. Text / Markdown → PDF Turn plain text or Markdown into a clean, downloadable PDF. Age Calculator Your exact age in years, months & days — plus next-birthday countdown and the day you were born. Aspect Ratio Calculator Solve width/height for any aspect ratio, with screen & video presets. BMI & Calorie Calculator BMI, BMR and daily calorie needs (TDEE) — metric & imperial. Budget Planner (50/30/20) Build a 50/30/20 budget from your income — customizable categories with a visual split. Calendar Event (.ics) Create an event and download a .ics for Google, Outlook & Apple Calendar. Calorie Calculator Daily calories (BMR & TDEE) with activity levels, goals & macro split — Mifflin-St Jeor. Chart Maker Paste data and get a clean bar, line, pie or donut chart — export PNG. Compound Interest Calculator Project savings & investment growth with contributions and a year-by-year chart. Countdown & Stopwatch A big countdown timer and stopwatch with alerts — for events & focus. Currency Converter Convert between 150+ currencies with editable offline rates (optional live update). Date Calculator Days between dates, add/subtract time, age & business-day counts. Day Planner (Time Blocking) Plan your day in time blocks on a visual schedule — saved locally. Decision Maker Can’t decide? Spin a wheel, pick a name, flip a coin or roll dice. Decision Matrix Score options against weighted criteria to find the best choice — saved locally. Eisenhower Matrix Prioritize tasks in urgent/important quadrants — drag between boxes, saved locally. Event Countdown Live countdowns to your big dates — exams, launches, weddings — multiple events, saved locally. Expense Tracker Log income & expenses by category with totals and a chart — private, export CSV. Flashcards Create study decks and review with flip cards & spaced repetition — local. Fuel Cost Calculator Trip fuel cost from distance, mileage & fuel price — round trips, cost split between passengers. Gantt Chart Plan a project timeline with tasks and a visual Gantt — export PNG. Goals & OKR Tracker Set objectives with measurable key results and track progress — stored locally. GPA Calculator Calculate weighted GPA from your courses, credits & grades. Grade Calculator Weighted course grades & “what do I need on the final?” — categories, weights, targets. Habit Tracker Build streaks with a clean habit grid — stored locally, never uploaded. Invoice Generator Create branded invoices with your logo and export to PDF — all free. Kanban Board A private kanban that saves to your browser. Export/import JSON. Loan & EMI Calculator EMI, total interest & a full amortization schedule for any loan or mortgage. Math Practice Timed arithmetic drills — choose operations & ranges, track accuracy and personal bests. Meeting Cost Calculator See what a meeting really costs — attendees × salary × time, live. Mind Map Brainstorm on an interactive mind map — add, drag, color & collapse nodes, export PNG/JSON. Notes A fast local notebook with Markdown — stays on your device. Percentage Calculator Percentages, % change, discounts and tax/VAT — all in one place. Periodic Table Interactive periodic table — search elements, view properties, categories & trends. Pomodoro Timer Focus timer with task list and session stats. Portfolio Maker Build a portfolio, CV or resume website from a simple form — 3 themes, live preview, one-file export ready for GitHub Pages. Project Board A beautiful Asana-style board — labels, assignees, due dates, subtasks & drag-drop. Saves locally. Random Number Generator Cryptographically random numbers — ranges, count, unique mode, sorting, lottery & dice presets. Random Team Generator Split a list of names into fair random groups or pairs — perfect for classrooms & teams. Resume Builder Fill in your details and export a clean, ATS-friendly resume PDF — saved locally. Salary Converter Convert pay between hourly, daily, weekly, monthly & annual — custom hours and weeks. Scientific Calculator A full scientific calculator with functions, memory & history. Sleep Calculator Find the best bedtime or wake-up time using 90-minute sleep cycles. Spreadsheet A mini spreadsheet with formulas (=SUM, =A1*B2…) and CSV import/export — runs locally. Statistics Calculator Paste numbers for mean, median, mode, std-dev, quartiles & a histogram. Subscription Tracker Track recurring subscriptions and see monthly & yearly totals — saved locally. Time Card Calculator Add up clock in/out times & breaks for daily/weekly hours, overtime & pay. Time Zone Converter Convert any date & time between time zones — DST-aware, with copy-ready results. Time Zone Planner Find the best meeting time across multiple time zones. Tip & Bill Splitter Split a bill with tip across any number of people, instantly. To-Do List A fast daily checklist that saves to your browser — priorities, due dates, drag to reorder. Typing Speed Test Measure your typing speed (WPM) and accuracy with timed tests — saved locally. Unit Converter Convert length, weight, temperature, area, data & more. Weekly Meal Planner Plan a week of meals on a grid and auto-build the grocery list — saved locally. Whiteboard An infinite canvas to sketch, add shapes, text & sticky notes — export PNG. World Clock Track the current time across multiple cities and time zones at a glance. Email List Cleaner Validate, dedupe & clean email lists locally — syntax checks, disposable-domain detection, CSV export. Hashtag Generator Turn keywords or a topic into relevant, ready-to-paste hashtags for social. Keyword Density Checker Analyze 1–3 word keyword frequencies & density in any text or HTML — with target-keyword tracking. On-Page SEO Checker Paste a page’s HTML for an instant on-page SEO audit — titles, headings, alts, OG & more. Social / OG Image Maker Design a 1200×630 social share image with title, gradient & logo — export PNG. URL Slug Generator Turn any title into a clean, SEO-friendly URL slug — bulk mode, separators & accent handling. X / Tweet Preview Compose with a weighted character counter (URLs = 23), thread splitter & live preview. YouTube Tag Generator Generate SEO-optimized YouTube tags from your video title — ranked, deduped, within the 500-character limit. Like RapidTags, but private. Base64 Encode/Decode Encode & decode text and files to/from Base64. Caesar / ROT13 Cipher Encrypt/decrypt with Caesar shift, ROT13 & Atbash — with brute-force decode. Code Formatter Beautify or minify JSON, CSS, HTML & JavaScript locally. Code Playground Write HTML, CSS & JS with a live preview and console — a local CodePen. Cron Expression Helper Translate a cron expression to plain English and preview the next run times. CSV ↔ JSON Convert CSV to JSON and back, in the browser. CSV Viewer & Editor Open a CSV as a sortable, filterable, editable table — export to CSV/JSON. cURL Converter Paste a curl command and get fetch, Axios, Python requests & PowerShell code instantly. Fancy Text Generator Turn text into 𝐛𝐨𝐥𝐝, 𝑖𝑡𝑎𝑙𝑖𝑐, 𝓈𝒸𝓇𝒾𝓅𝓉 & 20+ unicode styles — copy for bios & posts. Hash Generator SHA-1/256/384/512 of text or files via Web Crypto. HTML / CSS / JS Minifier Minify HTML, CSS & JS with safe whitespace/comment stripping — live size savings readout. HTML Entities Encoder Encode & decode HTML entities and escape special characters. JSON Diff Semantic JSON comparison — structural diff that ignores key order and shows added/removed/changed paths. JSON Formatter Beautify, minify & validate JSON instantly. JSON to TypeScript Turn JSON into TypeScript interfaces/types with flexible options — instantly. JWT Decoder Decode a JWT’s header & payload locally (no data sent). Markdown Editor Write Markdown with live preview & export to HTML. Markdown Table Generator Build a Markdown (or CSV/HTML) table from an editable grid. Morse Code Translator Translate text ↔ Morse code with adjustable audio playback & flashing. Number Base Converter Convert between binary, octal, decimal & hexadecimal. Number to Words Convert numbers to words — international & Indian (lakh/crore) systems, plus currency mode. Roman Numeral Converter Convert numbers to Roman numerals and back (1–3,999,999). SQL Formatter Beautify or minify SQL for many dialects — instant, local, no upload. SQL Playground Run SQL on an in-browser SQLite database; import CSVs as tables (one-time engine download). String Escaper Escape & unescape strings for JSON, JS, HTML, URL, SQL, CSV, regex & unicode. Text & File Encryptor Password-encrypt text or files with AES-256 (Web Crypto) — fully offline. Text ↔ Binary / Hex Convert text to binary, hex, octal, decimal or ASCII codes — and back. Text Cleaner & Line Tools Sort, dedupe, reverse, trim, find-replace & reformat lines of text. Text Diff Compare two texts and highlight every change. Text Summarizer Summarize long text into key sentences or bullets — adjustable length, fully on-device. Timestamp Converter Convert Unix timestamps ↔ human dates across time zones. URL Encoder & Parser Encode/decode URLs and break them into query parameters. UUID Generator Generate v4 UUIDs and ULIDs in bulk. XML Formatter Beautify, minify & validate XML, and convert XML ↔ JSON — in your browser. ZIP Extractor & Creator Open, inspect & extract ZIP files, or bundle your files into a new ZIP — locally. A/B Test Sample Size Calculator Free A/B test sample size calculator. Per-variation sample from baseline conversion rate + minimum detectable... Ad Creative Visual Hook Prompt Free ad creative prompt generator for Midjourney, Pencil, Adcreative.ai. Build platform-native Meta, TikTok,... Affiliate Commission Calculator Free affiliate commission calculator. Per-sale + monthly net (after fees), tier-bonus targets, recurring SaaS... Anchor Text Analyzer Free Shopify SEO anchor text keyword tool. Paste HTML, categorise anchors as branded / URL / generic /... AOV Calculator Free AOV calculator. Compute average order value, CM per order, channel AOV, and simulate revenue lift from... App Icon + App Store Prompt Free app icon prompt generator for App Store. Pick category, glyph, era, color, background; get Midjourney or... Article Schema Generator Free Article schema generator with URL + image fields. Fill form, copy JSON-LD aligned with Google Article... Backlink Signal Checker Free backlink verifier tools. Paste candidate URLs — fetches each, confirms link is live, reports anchor + rel... Blended CAC Calculator Free blended CAC calculator past Meta vendor dashboards. Sum paid, organic, tools, fees; divide by new... Bounce Rate Calculator Free Shopify bounce rate calculator. Single-page-session %, DTC / blog / B2B / SaaS benchmarks,... Box Shadows Generator Free CSS box-shadow generator with Material Design elevation presets. Stack up to 5 shadows layers, per-layer... Brand Voice Prompt Rules Generator Free brand voice prompt generator for ChatGPT, Claude, Gemini. Build a system prompt with voice archetype,... Breadcrumb Schema Generator Free BreadcrumbList schema generator for any home or page route. Build the navigation trail in JSON-LD with... Break-Even ROAS Calculator Free break-even ROAS calculator. Minimum ROAS to break even from contribution margin. Refund-adjusted floor +... Burn Multiple SaaS Calculator Free burn multiple SaaS calculator. Net burn / net new ARR per the David Sacks framework. SaaS verdict tiers +... Business Name Generator Free business name generator. Enter a keyword and industry; get 50 brand names across 5 styles: abstract,... Cache-Control + Max-Age Headers Checker Free cache headers + max-age checker. Paste curl -I, parses Cache-Control max-age, ETag, Last-Modified,... Canonical URL Checker Free canonical URL checker tool for Google SEO. Paste page HTML, extracts rel=canonical, validates absolute +... CDN Detector Free CDN + edge web detector. Paste curl -I, identifies Cloudflare, Fastly edge, CloudFront, Vercel, Netlify,... Churn Rate SaaS Calculator Free churn rate percent calculator for SaaS. Compute logo churn percent, revenue churn, net revenue retention... Shopify CMS Platform Detector Free CMS detector with platform-confidence score. Paste HTML source, we identify WordPress, Shopify,... SaaS Cohort Retention Calculator Free cohort retention calculator. 24-month survivor curve + half-life from monthly retention rate. SaaS / DTC... Brand Color Palette Extractor Free color palette extractor. Upload image, get dominant + 8-color palette. Hex, RGB, HSL output. Click swatch... Compression Detector Free compression detector + Vary headers audit. Paste curl -I, checks Content-Encoding (gzip / br / deflate /... Conversion Funnel + CVR Calculator Free 5-stage conversion funnel calculator. Identifies leakiest stage by benchmark gap, projects revenue from a... Conversion Rate Calculator Free conversion rate percent calculator with visitors lift. Compute CVR, revenue per visitor, category... Page Cookies Analyzer Free page cookies analyzer. Paste Set-Cookie headers, get name / domain / path / expiry / Secure / HttpOnly /... Core Web Vitals First Data Checker Free Core Web Vitals checker. First Contentful Paint, field data (28-day p75 from CrUX), lab data for LCP,... CORS URL Requests Checker Free CORS checker API tool. Real browser URL fetch from origin across 4 method requests. Reports exact CORS... CSP Validator Free Content Security Policy validator with scripts audit. Paste your CSP — get per-directive parsing for... CSS Google Size Checker Free CSS web development size checker for Google PSI. Live PSI lists every stylesheet with byte size + 1P/3P... CTR Calculator Free CTR organic position clicks calculator with 9 channel benchmarks (Google, Meta, Display, TikTok,... DAU MAU Users + SaaS Ratio Calculator Free DAU/MAU users stickiness calculator. 7 category benchmarks (messaging, social, productivity, B2B SaaS,... CNAME Lookup Free CNAME lookup tool for web development. Enter a hostname, queries Cloudflare DoH for canonical-name... DNS Domain DMARC Lookup Free DNS domain lookup .com tool. Live A, AAAA, MX, TXT, DMARC, NS, CNAME, CAA records via Cloudflare... MX Record Checker Tool Free MX record email checker tool. Enter a domain, queries Cloudflare DoH (1.1.1.1) for mail-server records,... DNS Propagation Cloudflare Google Tool Free DNS propagation checker tool. Queries Cloudflare 1.1.1.1 and Google 8.8.8.8 in parallel for the same... Domain Age + Registration Checker Free domain age checker. Cross-references the RDAP registration date with the Wayback Machine's first-capture... Domain Authority Checker Free domain authority checker, an alternative signal vs Moz DA + Ahrefs DR. Composite site-maturity score from... Domain Availability Checker Free domain availability checker tool. Live RDAP registry lookup tells you which registrar holds any .com /... Domain Health Checker Free composite domain health checker with grade. DNS signal (A/AAAA/MX/TXT), SSL status, domain age, Wayback... Profit + Percent Calculator Free ecommerce profit calculator. Enter revenue, COGS, shipping, fees, ads, fixed costs. Get gross margin... Email Design + Cart Prompt Free email design prompt generator for Klaviyo, Claude, v0.dev, Postscript. Build subject + preheader +... Email Monthly List Growth + Churn Calculator Free email list growth calculator. Projects subscribers over 12-24 mo from starting list, signup %, churn %.... Event Schema + Offers Generator Free Event schema generator with ISO dates. Venue + offers + status. Inline validator catches missing... External Links Counter Free external link counter. Paste HTML — splits internal vs external, audits rel attributes, flags missing... FAQ Schema Generator Free FAQPage schema generator with visible Google Rich result validator. Add unlimited Q+A pairs, valid... CSS Gradients Generator Free CSS gradients generator with multi-stop linear, radial, conic. Draggable position stops, live preview,... Google Heading Hierarchy Checker Free heading hierarchy checker per page for Google SEO. Paste HTML, parses H1-H6 page outline, flags multiple... Heading Page Outliner Services Free heading structure hierarchy outliner services for SEO. Paste HTML, get H1-H6 outline with warnings for... Hosting + Cloudflare Web Development Detector Free hosting provider web development detector. Live DoH lookup + ipapi.co ASN — identifies AWS, GCP, Azure,... Hreflang Links + Locale Checker Free hreflang checker. Paste your page HTML — extracts every rel=alternate hreflang tag, validates ISO codes,... Hreflang Generator Free hreflang generator for Google. Output HTML tags, XML sitemap xhtml:link, or HTTP headers. Built-in... HTTP Headers Checker Free HTTP headers checker. Paste curl -I or DevTools browser headers. Audits caching, CSP security (HSTS,... HTTP Status Code Checker Free HTTP status code checker. Type URL — live fetch returns status code, content-type, server, response time.... HTTP/2 + HTTP/3 Checker Free HTTP protocol checker. Paste curl -I — header audit identifies HTTP/1.1 vs HTTP/2 vs HTTP/3, validates... HTTPS / SSL / TLS Checker Free HTTPS / SSL / TLS checker for any domain. Live reachability + Certificate Transparency lookup (crt.sh)... Image Alt Text Checker Free image alt text checker. Paste HTML; we scan every <img> tag, flag missing alt, empty alt,... Image Format Checker Free image format checker. Paste HTML — scans every img tag for format (jpg/png/webp/avif/svg), lazy-loading,... Internal Link Counter Tool Free Shopify internal links counter tool. Paste page HTML — counts every internal vs external link, lists... IP Geolocation Lookup Free IP geolocation lookup tool. Enter IPv4 / IPv6 IPs — returns country, region, city, ISP, ASN, timezone.... IP Lookup Tool Free IP lookup tool. Resolves a domain to its A and AAAA records, then performs reverse DNS (PTR) on each IP... JavaScript Framework Detector Free JS framework detector tool. Paste HTML — identifies React, Vue, Angular, Svelte, plus state mgmt (Redux,... JavaScript Web Size Checker Free JavaScript web development size checker. Live PSI fetch lists every JS file with size + first-party vs... JSON Validator Free JSON validator with deep diagnostics. Paste JSON or NDJSON for strict parse, common-mistake detector,... Landing Page Prompt Book Free landing page prompt generator for v0.dev, Claude, Cursor. Book a 60-second Tailwind sections spec for any... Lighthouse Mobile Performance Checker Free Lighthouse audit + score checker for any URL. Mobile performance, SEO, Accessibility, Best Practices live... LocalBusiness Schema Generator Free Google LocalBusiness schema generator with address. Fill form, copy JSON-LD with address, geo coords,... Logo Prompt Generator Free logo prompt generator for any mark, monogram or wordmark. Pick brand archetype, style, color, form; get a... LTV Calculator Free LTV calculator. Enter AOV, purchase frequency, customer lifespan, and gross margin. Get gross LTV,... Markdown to HTML Free Markdown to HTML development converter. Live side-by-side preview, GFM CommonMark mode, copy HTML,... Markup Calculator Free markup calculator. Bidirectional entry (markup percent, margin percent, or selling price). Industry... Meta Description Checker Free Google meta description checker tool. Paste description or full HTML; we check length (120-155 char),... Mobile-Friendly Test Free mobile-friendly test. Live Google PSI mobile audit — checks viewport, tap targets, font size, content... MRR ARR Calculator Free SaaS MRR + ARR development calculator. Compute monthly recurring revenue, annualized ARR, net new MRR,... Multi-URL Audit Free bulk SEO audit. Run Google PSI on up to 5 URLs in sequence — comparison table of Performance, SEO,... Open Graph Image Card Preview Free Open Graph image preview card tool. Test how OG cards and tags render on Facebook, X, LinkedIn, Slack,... Packaging Design Prompt Generator Free packaging design prompt generator. Pick product, brand vertical, material, print style, color, and... Page Weight Analyzer Free page weight analyzer for web development. PSI byte breakdown by type — HTML, CSS, JS, image, font,... CAC Payback Calculator Free CAC payback calculator with contribution margin. Enter AOV, repeat rate, gross margin, CAC. Get months to... Product Photo Prompt Style Free product photo prompt generator for Nano Banana, Midjourney, Imagen. Build subject + lighting + camera +... Product Schema Generator Free Product schema generator. Fill the form, copy JSON-LD with offers, aggregateRating, brand, GTIN/SKU.... Purchase Order Generator Free purchase order generator. Issue a buyer-side PO with vendor, ship-to, line items, terms, delivery date.... Quote Generator Free quote generator. Build a priced quote with line items, tax, discount, and notes. Download as a branded... Reading Time Calculator Free reading time WPM calculator with figure-aware count. Live count of words and content reading time across... Receipt Generator Free receipt generator. Log a payment with buyer, payer, method, amount, balance, and item detail. Download as... Redirect Chain Checker Free HTTP redirect chain checker. Paste curl -ILv output — traces 301/302/307/308 redirects hops, flags chain... Render Blocking Checker Free render-blocking resources checker. Live PSI web development LCP audit lists every CSS / JS file blocking... Review Schema Generator Free Reviews schema generator for Google rich results. Fill the form for individual Review or aggregate... ROAS Calculator Free ROAS calculator. Compute per-channel ROAS across Meta, Google, TikTok, and affiliate. Get blended ROAS... Robots.txt Tester Free robots.txt disallow tester. Paste robots.txt and a URL; we run the live RFC 9309 longest-match for... Runway Calculator Free startup runway calculator with cash scenarios. Enter cash on hand, monthly burn, monthly revenue — live... SaaS LTV:CAC Ratio Calculator Free SaaS LTV:CAC ratio calculator with monthly churn. Lifetime value, customer acquisition cost, payback... SaaS Magic Number Calculator Free SaaS magic number calculator. Sales efficiency from new quarter ARR + S&M spend. Verdict bands at 0.5 /... SaaS Quick Ratio Calculator Free SaaS Quick Ratio MRR calculator. (New + Expansion MRR) / (Churned + Contraction). Stage churn verdict for... Shopify Discount URL Generator Free Shopify discount URL generator. Build auto-apply discount share links with optional product, redirect... Shopify ROI Calculator Free Shopify rebuild ROI calculator. Enter GMV, conversion lift percent, AOV lift, build cost. Get payback... Shopify Speed Score Test Free Shopify speed test with score. PageSpeed data, Shopify apps detection (Klaviyo, Yotpo, Judge.me), Core... Site Health Checker Free site health checker via Google Lighthouse PSI. 4-cat composite (Performance + SEO + A11y + Best... Slogan Generator Free slogan generator for product brands. Enter your brand and offering; get 40 slogans and taglines across 5... Social Post Prompt Generator Free social post prompt generator. Pick platform, goal, format, voice, length, CTA, and hashtag style; get a... SOW Generator Free SOW generator for client work. Build statement with scope, deliverables, milestones, acceptance criteria,... SPF DKIM DMARC Checker Tool Free SPF, DKIM, and DMARC checker tool. Enter a domain — queries Cloudflare DoH for the email-auth TXT records... SSL Certificate Inspector Free SSL certificate inspector tool. Pulls the most-recent cert from public Certificate Transparency logs... SSL Expiry Monitor Tool Free SSL expiry monitor tool. Paste up to 20 hostnames at once for cert expiry — days-remaining + renewal... Structured Data Validator Tool Free structured data validator tool. Paste JSON-LD or microdata; we parse, walk every node, and check required... Subdomain Finder Tool Free subdomain finder tool. Enumerates every public sub-domain .com ever issued an SSL certificate via crt.sh... SVG Optimizer Tool Free SVG optimizer tool. Strip XML comments, editor metadata (Inkscape, Adobe, Sketch), redundant default... Tech Stack Detector Tools Free tech stack detector tools. Paste HTML — we identify JS framework, CSS framework, analytics, payment, ads,... Title Case Converter Free title case converter with AP, Chicago, MLA, APA, NYT, Wikipedia sentence-case modes. Handles prepositions... Title Tag Checker Free title tag checker brand keyword tool. Paste a title or full HTML; we run length, pixel-width,... Twitter Card Validator Free Twitter Card validator with summary preview. Paste page HTML — extracts every twitter:card / title /... User Agent Parser Free user agent parser tool. Paste a UA string — Chrome/Mozilla version, browser, OS, device, engine, bot... Wayback Archive Viewer Free Wayback Machine viewer tool. Find the first archived domain URL capture plus year-by-year snapshots back... Web Server Detector Free web server CDN origin stack detector. Paste Server / X-Powered-By / response headers — we identify nginx,... Website Audit Free website audit tool. Enter a URL, get a Digital-Heroes-branded scorecard across Performance, SEO,... Website Hero Prompt Generator Free website hero prompt generator for v0.dev, Claude Design, Cursor, Lovable. Build a hero brief with primary... WHOIS Lookup Free WHOIS lookup. Real registrar, creation date, expiration, name servers, and status from the live RDAP... XML Sitemap Validator Free XML sitemap URLs validator. Paste a sitemap.xml; we parse it, check urlset namespace, validate every URLs...

No matches? Request a tool — we ship new ones every month.

§ 05 · why free

No signup, no email, no dashboard.

Every tool on this page runs entirely in the browser using standard Web APIs. No server receives the numbers you enter. No analytics beacon carries your business data to a third party. No account gates the output. The tools that pay for themselves on DH's side are the ones honest operators use and share; the ones that try to extract email addresses rarely make it to that group. Performance budgets follow Google's Page Experience signals.

01 · private

Browser-only.

Every value you enter lives in memory for the tab you opened. Close it and the data is gone. Nothing is stored, synced, or transmitted.

02 · portable

Copy-and-paste output.

Every tool has a "Copy results" button that puts a clean plain-text summary on your clipboard, ready to paste into a board deck, a Slack message, or an email.

03 · honest

Verdict lines, not sales pitches.

Each tool names the bracket your number falls into and what the next action usually is. If the honest answer is "this is fine, no work needed", the verdict says that.

Editorial seal of craft: hand-drawn moss-green double-ring stamp with laurel leaves, centred text NO SIGNUP / BROWSER ONLY / OPEN SOURCE, small amber orb marker
Fig. 03 · seal of craft
§ 06 · the principle

We earn clients through usefulness, not friction.

Most "free" tool sites gate results behind a signup wall, inject a chat widget that pulls you into a sales funnel, or save your numbers server-side for retargeting. We don't. The tools here work end-to-end without an account, and none of your inputs leave your browser. Accessibility follows the WCAG 2.1 quick reference, and feature support is verified against Can I Use before shipping. The ones that send us business are the ones an operator uses at 11pm on a Tuesday and shares with a colleague at 9am Wednesday.

"The invoice generator is the first one I've used where I didn't have to watch for an upgrade dialog. I bookmarked it on three machines."

operator feedback · DTC founder, London

Published · Last updated .