Caesar & ROT13 cipher. Encode, decode, crack.
Encode and decode Caesar, ROT13, ROT47, Atbash and A1Z26 ciphers live, or crack an unknown shift with a frequency-scored brute-force panel. Everything runs in your browser; your text is never uploaded.
A free online tool by Digital HeroesBetween letters of a word, e.g. 8-5-12-12-15.
Between words. Decoding reads any digits it finds.
This cipher is self-inverse: encoding and decoding are the same operation.
Everything runs on your device. Your text never leaves the browser.
Brute-force Caesar
All 25 shifts of the input, scored by English letter frequency (χ², lower is more likely English). Top 3 are highlighted. Click a row to copy its full text.
Classic ciphers, cracked live
The Caesar cipher rotates each letter a fixed number of places through the alphabet, ROT13 is simply a Caesar shift of 13, which makes it its own inverse. ROT47 extends the idea to all printable ASCII, Atbash mirrors the alphabet (A↔Z), and A1Z26 swaps letters for their positions. None of them are secure by modern standards, there are only 25 possible Caesar keys, which is exactly what the brute-force panel demonstrates by decoding all of them at once and ranking each candidate against English letter frequencies. Great for puzzles, geocaching, CTF warm-ups and teaching the basics of cryptanalysis.
Five ciphers, one workbench.
- Encrypt or decrypt with a custom Caesar shift from −25 to +25, updated live as you drag the slider.
- Apply ROT13, ROT47 or Atbash with a single click, the tool knows they're self-inverse, so there's no mode to get wrong.
- Encode and decode A1Z26 (letters as numbers) with custom letter and word separators; decoding reads any digits it finds.
- Crack unknown Caesar ciphers with the brute-force panel: all 25 shifts scored by English letter frequency, top 3 flagged.
- Control the output, preserve or flatten letter case and keep or strip non-letter characters.
- Copy, download or chain: copy the result, save it as a .txt file, or feed the output back into the input with one click.
Five steps, no manual.
- Pick a cipher, Caesar, ROT13, ROT47, Atbash or A1Z26, and choose Encode or Decode.
- Type or paste your text. The output updates live as you type.
- For Caesar, drag the shift slider (−25 to +25). For A1Z26, set your letter and word separators.
- Don't know the shift? Check the brute-force panel, all 25 candidates ranked by how English they look; click any row to copy it.
- Copy or download the result, or hit “Use output as input” to chain another pass. Nothing is uploaded.
Frequently asked questions.
Is the Caesar / ROT13 cipher tool free?
Is it private? Is my text uploaded anywhere?
Which ciphers does it support?
How does the brute-force panel rank the shifts?
What's the difference between ROT13 and ROT47?
Is a Caesar cipher secure for sensitive data?
Published · Last updated .
