Cross-Platform Mobile App Development Services: Top 9 Firms

the short answer

Our order for a business building its first iPhone and Android app: Digital Heroes, Callstack, Software Mansion, Very Good Ventures, Infinite Red, LeanCode, Touchlab, Simpalm and Rishabh Software. Choose the framework before the firm: Callstack, Software Mansion and Infinite Red for React Native, Very Good Ventures and LeanCode for Flutter, Touchlab for Kotlin Multiplatform, and Simpalm or Rishabh when you want several frameworks under one roof.

We wrote this page and ranked ourselves first. The full disclosure follows the six criteria, before the list starts, and our own entry names the firms that beat us on depth.

§ 01 · how we ranked

Two stores, one codebase, six criteria. All fixed before the ranking.

Every firm here promises one codebase for iPhone and Android. The differences surface later: when the app needs something the framework does not draw for you, when Apple or Google moves a deadline, and when you take the code to another team. These criteria look at those moments rather than at the sales deck.

What we looked for on each firm's own site

A framework answer with a reason. Which framework the firm would use for your app, when it would tell you to go native instead, and which one it sells by default.
Native depth. Swift and Kotlin written inside a shared codebase for the parts the framework cannot do, such as widgets, Live Activities, Bluetooth or video, shown in work it names.
Apps you can download. Named apps in the App Store and Google Play, with the part this firm actually built.
An upkeep plan. A written answer for the yearly Apple and Google deadlines and the framework's own upgrades, with a line in the budget.
Ownership and exit. Repositories, cloud accounts and store listings held by you, and a handover another team can pick up.
Where people sit. The address on the firm's own site, where the engineers work, and the hours they answer.

Weighted for a business paying for its first app on both stores. A company that already runs a large app, or two native teams, would weight native depth and upkeep higher, and would get a different order.

disclosure

Now the disclosure, because a list that hides who wrote it is an advert. Digital Heroes compiled this page and put itself in first place. The scores are our assessment against the six criteria above rather than measured performance, we did not test any competitor.

We read the other eight firms on their own websites on 17 October 2026 and took nothing from anywhere else. Nobody paid to appear, there are no affiliate links, no competitor is linked from this page, and we print no ratings or review counts for them. Two things count against us: our engineers are not in the United States, and our entry names no open-source library of ours, while six firms below maintain one.

§ 02 · the ranking

The nine firms, in our order.

Every entry starts with where the firm says it is and the framework it leads with, then the work you can check today and the buyer who should look elsewhere.

pick 01 · written by us

Digital Heroes

New York head office without engineers; build teams in Delhi and Lucknow, plus mobile engineers in Sydney · since 2017 · React Native by default

Our first place is for one kind of buyer: a business paying for its first app on both stores, which wants a single firm to carry it from scope to release and wants the contract on its side. Our CTO, Divyansh Singh, made React Native the team's default whenever an app must run on iOS and Android, so our advice leans that way unless your app needs something it handles badly.

The work we can name is the AirTrainr athlete and trainer apps, built in React Native with Expo and Supabase. That is also the weak spot. It is our one named cross-platform build on this page, we have no Flutter or Kotlin Multiplatform app to show you, and six firms below maintain libraries that other teams install, which we cannot match.

We lead on terms. A paid two-week discovery comes first, then a fixed price. You hold the repositories and cloud accounts from sprint one, a week without a recorded demo of working code goes unbilled, and the code we write for you becomes yours when the final invoice is paid.

Our New York office at 1140 Broadway holds leadership and account directors, not engineers, and replies on the same business day; its hours are 9 AM to 6 PM Eastern. Our Clutch profile shows 5.0 from 66 verified reviews (checked 13 October 2026). How we run an app build, platform by platform, is on our mobile app development page.

Fits: a company launching its first iOS and Android app with a backend, on a fixed scope, that wants answers in Eastern business hours and the code kept in accounts under its own name.

Does not fit: a large React Native app already in trouble, where Callstack or Software Mansion bring framework depth we do not; a team set on Flutter or Kotlin Multiplatform; and contracts that require engineers inside the United States, which Infinite Red offers and we do not.

pick 02

Callstack

Wroclaw, Poland, the only address on its site · founded 2016 · React Native, React and native engineering

Callstack opened in Wroclaw in 2016, a few months after React Native went public. Its about page counts more than 300 commits to the framework and says it was a founding member of the React Foundation. React Navigation and React Native Paper are among the open-source libraries it maintains, and it says it passed 200 people in 2024.

Its case studies run at enterprise size: moving AutoZone's iOS and Android apps to React Native, putting one React Native codebase on five TV platforms for a Samsung TV launch, and training HelloFresh engineers. The service page promises engineers in your codebase within the first week, help with stalled New Architecture upgrades, and that you own everything it builds.

Fits: companies with a React Native app at scale and a hard problem: a stalled upgrade, slow screens, React Native added to an existing native app, or a move onto TVs and other screens.

Does not fit: a first app on a small fixed budget, which its enterprise case list does not show; Flutter projects; and buyers who want an office in their own country, since the site names only Wroclaw and offers flexible time zone coverage instead.

pick 03

Software Mansion

Krakow, Poland, listed on NewConnect · 14 years in custom software · 400+ people

Software Mansion presents itself as one of the firms at the centre of React Native's development, and names itself a co-creator of the React Foundation. Its tools include Reanimated and React Native ExecuTorch, which runs PyTorch models on the phone itself. Mobile is one practice among several: the same firm works in Elixir, live video, web apps and AI.

Its Partiful case shows the native depth. To bring the Android app level with iOS, the team built transparent video natively on Android, because the player behind the usual React Native video libraries drops the alpha channel, and rendered it with OpenGL. It then added Live Activities to the iOS app in Swift and SwiftUI.

Fits: React Native apps that need native work the framework does not cover, such as custom video, heavy animation, gestures or models running on the device.

Does not fit: Flutter or .NET projects, and buyers who want a local office, as the contact page gives one address, in Krakow. With 400+ people across several practices, ask who on your account works on mobile full time.

pick 04

Very Good Ventures

No office address; a fully remote team of 120+ · started 2018 · Flutter first

Very Good Ventures' founders shipped the first commercial Flutter app, for Hamilton: The Musical, in 2018, and the firm says Google trusted it with the Flutter Gallery and the Google I/O conference app. It lists six Google Developer Experts on staff, maintains packages such as very_good_cli and very_good_analysis, and writes unit, widget and integration tests for every feature.

Its recent cases lean to migration: Scooter's Coffee's separate native iOS and Android apps moved into Flutter with a multi-agent AI pipeline, plus Flutter apps for Universal Destinations, the air carrier JSX and Blade. It describes its clients as mid-market and enterprise brands and counts more than 250 projects.

Fits: mid-market and enterprise brands choosing Flutter, especially those folding two native apps into one codebase or adding web and desktop from the same code.

Does not fit: teams committed to React Native, since its pitch, tools and case list are Flutter; early startups below the mid-market clients it names; and anyone who wants to meet the team in an office, because it has none.

pick 05

Infinite Red

Fully remote across the United States · over a decade in software · React Native, Expo, Swift and Kotlin

The pick for a team that is entirely in the US. Infinite Red says its engineers average 15 years of experience, that it hires mostly at senior level, and that three of its people sit on the React Native core team. It has more than 75 React Native projects behind it, maintains Ignite and Reactotron, and has run the Chain React conference in Portland, Oregon, since 2017.

Named work includes more than a year with Microsoft on Bluejeans, a video messaging app, a bulk freight app for BulkLoads, and a Mercari case study. Besides new builds, it sells audits of existing React Native code and planned version upgrades.

Fits: US companies whose contracts, data rules or comfort call for a team inside the United States, building or rescuing a React Native and Expo app.

Does not fit: Flutter or Kotlin Multiplatform work, and programs that need several squads at once, as its team page lists fewer than 30 people. There is no office to visit; the whole team works remotely.

pick 06

LeanCode

Warsaw, Poland, its only address · Flutter as core technology since 2018 · 80+ experts

LeanCode is the bank-scale Flutter pick. For Credit Agricole Bank Polska it put 30 Flutter developers on the CA24 Mobile banking app for 12 months. It says it appears among the recommended Flutter consultants on flutter.dev, employs two Google Developer Experts for Dart and Flutter, and has finished more than 60 Flutter projects.

Its own open-source project, Patrol, is a Flutter UI testing framework that can operate the phone itself, opening the notification shade or switching Wi-Fi and location, so tests cover what a real user does. The firm also moves apps to Flutter from Xamarin, .NET MAUI and React Native.

Fits: banks, fintechs and large companies that want a big Flutter team with automated UI testing, and owners of a Xamarin app heading to Flutter.

Does not fit: React Native shops, since its Flutter page calls Flutter the default for new apps and sells React Native to Flutter migrations, and US buyers who want a US address; the site gives only Warsaw.

pick 07

Touchlab

1216 Broadway, New York · Kotlin Multiplatform in production since 2018 · Kotlin Foundation member

Touchlab takes the other road. Instead of one shared interface, Kotlin Multiplatform shares the business logic in Kotlin and keeps a fully native interface on each platform. Touchlab is the team behind SKIE and xcode-kotlin, tools for working with shared Kotlin from Swift and Xcode, and has put KMP code into production since 2018.

Its offers can start small: a quick assessment of a KMP codebase, a best-practice code review, or a roadmap with a proof of concept, beside full development. Its adoption guide is written for teams of more than two native developers who keep native screens and add shared code, which says plainly who it serves best.

Fits: companies with separate iOS and Android teams that want to stop writing the same logic twice without changing either interface, and teams whose KMP setup has started to slow them down.

Does not fit: a first app from a small team that wants one interface written once, which is React Native or Flutter work. Its open role is for a pool of remote contractors, so ask who will staff your project.

pick 08

Simpalm

Offices in Rockville, Maryland, Tysons, Virginia, Chicago and New York · founded 2010 · React Native, Flutter, .NET MAUI and Ionic

Simpalm suits a US buyer who wants an office nearby, several frameworks and prices in writing. Its about page lists four regional offices: Rockville, Maryland, Tysons, Virginia, Chicago and New York. It builds in React Native, Flutter, .NET MAUI and Ionic, offers fixed cost, time and materials or dedicated teams, and offers to sign your NDA.

It publishes ranges most firms keep private: about $20,000 to $45,000 for a simple cross-platform MVP and $70,000 to $100,000 for advanced apps, with an MVP taking 8 to 12 weeks. Its named apps include the Mercy Prayerbook, rebuilt for iOS and Android for the Sisters of Mercy of the Americas, and an online safety app for CASSA.

Fits: US nonprofits, startups and mid-sized firms that want a nearby office, a fixed-cost option and a price range in writing up front; also .NET teams choosing MAUI.

Does not fit: apps whose core is native platform work such as custom video or widgets. Simpalm's own FAQ warns that cross-platform may not suit performance-heavy apps needing high-end native features, and the cases it shows are content and community apps.

pick 09

Rishabh Software

Headquartered in Vadodara, India, with offices in Ahmedabad, Pune, Hyderabad, Bengaluru, Round Rock, Texas and Harrow, UK · founded 2000 · 800+ professionals

The longest framework list here: Flutter, React Native, .NET MAUI, Kotlin Multiplatform, Ionic, NativeScript and Cordova. Its distinctive work is getting apps off Xamarin. Cases on its page include a healthcare app for an Australian public sector body, moved off Xamarin onto .NET 8, and a Xamarin to MAUI migration for a US data logger manufacturer.

It also shows apps that talk to devices: an NFC-enabled smart insulin pen app built in Flutter around a native SDK, and a Flutter smartwatch companion for an Irish IoT company. Beside the offices above, it lists an Australian phone line, and its about page counts more than 800 professionals across eight locations.

Fits: Microsoft-stack companies with a Xamarin app to move, and device makers whose app talks to NFC, Bluetooth or wearables, who want one vendor across several frameworks.

Does not fit: buyers who want a mobile-only studio, since mobile sits beside data analytics, BI, GenAI and Microsoft workplace services. Five of its seven addresses are in India, so ask where your engineers will sit and agree meeting hours before you sign.

Nine entries, not ten. We read two more firms' pages today and left both off: one still lists Xamarin among its tools for new apps, and the other's cross-platform page names no shipped app we could tie to a framework.

§ 03 · at a glance

All nine on one screen. Framework first, catch last.

The work column lists what you can look up before any call. If it reads thin for a firm you like, make it the first thing you ask that firm about.

Cross-platform app firms in their own words, from their websites on 17 October 2026
#	Firm	Leads with	Base on its site	Work you can check	Does not fit
01	Digital Heroes	React Native with Expo	New York; engineers in India and Sydney	AirTrainr apps	A large app already in trouble
02	Callstack	React Native	Wroclaw, Poland	AutoZone migration, five TV platforms	A small fixed-budget first app
03	Software Mansion	React Native	Krakow, Poland	Partiful native video, Live Activities	Flutter or .NET work
04	Very Good Ventures	Flutter	Remote, no office	Hamilton app, Scooter's Coffee migration	React Native teams
05	Infinite Red	React Native with Expo	Remote, US only	Bluejeans with Microsoft, BulkLoads	Several squads at once
06	LeanCode	Flutter	Warsaw, Poland	CA24 Mobile banking app, Patrol	React Native shops
07	Touchlab	Kotlin Multiplatform	New York	SKIE, xcode-kotlin	One small team wanting one interface
08	Simpalm	React Native, Flutter, MAUI, Ionic	Rockville, Tysons, Chicago, New York	Mercy Prayerbook, CASSA	Apps built on native features
09	Rishabh Software	Seven frameworks, MAUI and KMP among them	Vadodara, India; Round Rock, Texas	Xamarin migrations, NFC insulin pen app	A mobile-only studio

§ 04 · framework first

Pick the framework, then the firm. It halves the shortlist.

Seven of the nine firms, ours included, lead with one framework and argue for it. That is fine once you know it before the sales call. The table gives each option's status as its maintainer states it, so any claim you hear can be checked at the source.

Cross-platform frameworks, with status taken from each maintainer's own documentation, read 17 October 2026
Framework	Language	What is shared	Status at the source	Firms here that lead with it
React Native	JavaScript or TypeScript	Screens and logic, shown with each platform's own interface parts	Runs only on the New Architecture since version 0.82; the docs recommend starting with Expo	Digital Heroes, Callstack, Software Mansion, Infinite Red
Flutter	Dart	Screens and logic, drawn by Flutter itself so they look the same everywhere	Version 3.47 supports Android API levels 24 to 37 and iOS 15 to 27, plus Windows, macOS, Linux and the web	Very Good Ventures, LeanCode
Kotlin Multiplatform	Kotlin	Logic; screens stay native, or are shared through Compose Multiplatform	Android and iOS rated Stable, and Compose Multiplatform on iOS Stable too	Touchlab
.NET MAUI	C#	Screens and logic	Each major version supported for at least six months after the next one ships	None lead with it; Simpalm and Rishabh offer it
Xamarin	C#	Screens and logic, through Xamarin.Forms	Support ended on 1 May 2024; its last targets are Android API 34 and Xcode 15	Migration only: LeanCode, Rishabh

If your developers write React or TypeScript, React Native lets them read and change the app after the build team hands it over, and Expo, the starting point the React Native docs now recommend, makes version upgrades easier. If you want the interface to look identical on every phone, or to reach desktop and the web from the same code, Flutter is built for that. Our React Native and Flutter pages cover each in depth.

Kotlin Multiplatform suits a company that already has strong iOS and Android teams and wants them to stop writing the same logic twice. .NET MAUI suits a C# shop willing to take a major upgrade every year. And if a proposal names Xamarin for new work, stop reading: its last Android target is API 34, while Google Play has required app updates to target API 36 since 31 August 2026.

§ 05 · the upkeep calendar

One codebase, three calendars. Apple, Google and the framework.

Sharing code cuts what you write, not the deadlines you meet. Each store sets its own rules for what it accepts, the framework ships on its own schedule, and an app nobody touches for a year can drift out of a store's requirements. These are the dates on Apple's, Google's and each framework's own pages, as read on 17 October 2026.

Apple's build tools

Since 28 April 2026, every app uploaded to App Store Connect must be built with Xcode 26 or later on the iOS 26 SDK, according to Apple's upcoming requirements page. When Apple raises that minimum, an app with no new features still needs a rebuild before it can ship a fix.

Google Play's target level

From 31 August 2026, new apps and updates must target Android 16, API level 36, with an extension available to 1 November 2026. Existing apps aimed below API 35 stop reaching new users on newer phones. The rule sits on Google's target API level page.

React Native's releases

Version 0.82, out on 8 October 2025, runs only on the New Architecture; 0.81 and Expo SDK 54 were the last releases that allowed the old one. Releases kept coming in 2026, with 0.86 in June and 0.87 in August, so an untouched app falls several versions behind inside a year.

MAUI and Flutter

Microsoft supports each .NET MAUI major for at least six months after the next one ships, which in practice means an upgrade a year; the current one came out on 11 November 2025. Flutter's supported list moves with its releases: as of 3.47 it covers iOS 15 to 27 and Android API levels 24 to 37.

Ask every firm for its upkeep plan in writing: who watches these dates, how many days a year the upgrades take, and the price. Our mobile app cost calculator budgets upkeep at 15% to 20% of the build each year, drawn from our team's own pricing guide.

§ 06 · how to choose

Score three replies. Then hand over one native feature.

Put the same brief in front of three firms. One page is enough: the job the app does, who opens it and how often, each system it talks to, the phone features it needs and the budget you can defend. Mark every answer out of five per row, weight the marks, and write down what evidence each firm actually showed you.

A weighted scorecard for cross-platform app proposals, built on the six criteria this ranking used
Criterion	Weight	What to ask for
A framework answer with a reason	20%	The framework proposed for your app, the case against going native, and the framework the firm sells most
Native depth	20%	Swift or Kotlin the firm wrote inside a cross-platform app, and the store listing of the app it shipped in
Apps you can download	20%	Two named apps in both stores, and which screens and services this firm built
An upkeep plan	15%	Who tracks the Apple, Google and framework dates, the days a year it takes, and the price
Ownership and exit	15%	Repositories, cloud accounts and both store accounts in your name, with the handover pack written into the contract
Where people sit	10%	The office that replies to you, where your engineers work, and the hours that overlap your day

The native feature test

Pick one feature your app needs that the framework will not draw for you: a home screen widget, a Live Activity, a Bluetooth device, or a camera flow that must work offline. Ask each firm how it would build that, in which language, and which app it shipped already does something close.

A firm with native depth names the module, the Swift or Kotlin it would write, and the test it would run on a real phone. A firm without it tells you there is a plugin for that.

Make the quotes line up

Ask for the backend, the design, the store release work and the first year of upkeep as separate lines. Then read what each quote leaves out, and check whether the lowest total skips upkeep, testing on real phones or the store setup.

Starting from nothing? Test the idea with our app idea validator, draft the brief in the requirements document generator, and run each total through the quote checker to see the hourly rate it implies.

§ 07 · cost

What one app on two stores costs. And what the shared code saves.

Our mobile app cost calculator, built on the pricing guide our team wrote, prices the scope on one native platform and then applies a platform factor. Its focused MVP band is $40,000 to $80,000 across 3 to 5 months. A mid-complexity business app sits at $90,000 to $180,000 across 5 to 8 months, and advanced or enterprise apps at $200,000 to $500,000 or more across 8 to 18 months.

The factor is where cross-platform pays. One React Native or Flutter codebase for both stores comes out at 1.1 to 1.3 times the single-platform band, and two native apps at 1.7 to 1.9 times. At the midpoints, that is about a third less for the same scope. Vendors' own claims spread wider: NIX United puts the upfront saving at 10 to 30 percent, Simpalm at 30 to 40.

Among the other eight, Simpalm and LeanCode publish price bands on the pages we read. Simpalm's simple MVP at $20,000 to $45,000 starts at half our calculator's floor; LeanCode advises keeping a Flutter MVP between €50,000 and €150,000, with support plans from €300 a month. Compare what each band includes before you compare totals. Then add Apple's $99 a year and Google Play's one-time $25 for the store accounts, and the upkeep that follows launch.

Native modules, because every feature the framework does not draw, such as widgets, Live Activities or Bluetooth, is Swift and Kotlin work with its own price.
The backend, which the calculator prices at $25,000 to $80,000 when your app needs its own API rather than a managed service.
Real-time features, such as chat, presence or live sync, at $15,000 to $40,000.
Compliance, where HIPAA health data adds $30,000 to $100,000 in the calculator and PCI-DSS card handling $15,000 to $40,000.

These are planning ranges, not quotes. For a fixed number, book the free 30-minute call; the build price itself is set after a two-week discovery. Hiring one developer instead of a team? Read how hiring a mobile developer from us works.

§ 08 · questions

What buyers ask before they choose.

How can I develop a cross-platform mobile app?

Choose the framework by who will maintain the app: React Native for a team that writes React, Flutter for an interface that must look identical everywhere, Kotlin Multiplatform when you already run native teams. Then scope one core flow, build it with the native modules it needs, and test on real iPhones and Android phones. Release through TestFlight and a Google Play test track, and budget for the yearly store and framework upgrades.

How much does it cost to hire a mobile app developer?

It turns on seniority and where the developer works. The pricing guide behind our mobile app cost calculator puts junior developers at $35 to $60 an hour, mid-level at $60 to $100, senior at $100 to $160 and a technical lead at $150 to $220. Simpalm's FAQ puts US-based firms at about $120 to $200 an hour. Our hire mobile app developers page covers vetting and contracts.

What is a cross-platform app developer?

An engineer who writes one codebase that runs on both iOS and Android, usually in React Native, Flutter, Kotlin Multiplatform or .NET MAUI. A good one still reads Swift and Kotlin, because widgets, Live Activities and Bluetooth often need native code, and knows both stores' release tools: TestFlight and App Store Connect on one side, the Play Console on the other.

What are the best cross-platform app development services available?

The best one depends on your framework and your app. For a first build on both stores at a fixed scope, we rank ourselves first and say why above. For deep React Native work, look at Callstack, Software Mansion or the US-based Infinite Red; for Flutter, Very Good Ventures or LeanCode; for shared Kotlin logic under native screens, Touchlab.

React Native or Flutter: which suits a business app?

Either can carry one. Choose React Native if your developers already write React or TypeScript, or if you want each platform's own interface parts; its docs recommend starting with Expo. Choose Flutter for an interface that looks the same on every phone, and for desktop or web from the same code. The question that settles it is who will maintain the app three years from now.

Can one shared codebase still use widgets, Live Activities or Bluetooth?

Yes, through native modules written in Swift for iOS and Kotlin for Android and called from the shared code. Software Mansion added Live Activities to Partiful's React Native app this way, and Rishabh Software built a Flutter insulin pen app around a native SDK. Expect each such feature to be priced and tested on its own.

What should we do with an app still built on Xamarin?

Plan the move now. Microsoft ended Xamarin support on 1 May 2024 and its last Android target is API 34, while Google Play has required updates to target API 36 since 31 August 2026, with extensions only to 1 November 2026. Microsoft names .NET MAUI as the successor to Xamarin.Forms, which suits a C# team; others rebuild in Flutter or React Native. LeanCode sells Xamarin to Flutter moves, Rishabh Software Xamarin to MAUI.

When is native better than cross-platform?

When most of the app is platform features rather than screens: heavy camera or AR work, deep health or watch integration, or an interface that must adopt each new iOS design on release day. Native is also the sensible default when you already run strong iOS and Android teams, and Kotlin Multiplatform can then share logic without a rewrite. For a typical business app, one shared codebase is the cheaper start.

Last reviewed 17 October 2026.

§ 09 · score us too

Give us the brief the others get. Mark our answer last.

Thirty minutes on a call costs you nothing, and if the work suits us, you have a written scope and a quote within 48 hours. Mark it on the scorecard against two rivals. If a firm above suits your app better, the marks will show it, and you should hire that firm.

Book a call with a tech lead Our mobile app work React Native development

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Why work with Digital Heroes

115 people across five studios in New York, Delhi, London, Sydney and Lucknow, shipping ecommerce, web, software and mobile work for founder-led brands. Senior engineers only, no account-manager relay, and the same team from kickoff to launch.

Shopify Select Partner, as listed in the Shopify Partner Directory
Tier 1 registered supplier on the United Nations Global Marketplace, which requires audited company documentation
Top Rated Plus on Upwork, the bracket for the top 3% of talent by client outcomes
397 public five-star-weighted reviews across four Fiverr gigs, from clients in 36 countries
DUNS verified business, No. 650878346, so procurement can check us before signing
Listed by Clutch in Top 1000 Global B2B Companies and Top Web Designers 2024
Verified profiles on GoodFirms, DesignRush, Digital.com, AppFutura and TopDevelopers
2,000+ brands built across 40+ countries, with $50M+ in client revenue scaled

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Cross-platform mobile app development services, ranked. Nine firms, and the app each one suits.