ROT13 / Caesar Cipher
Encode or decode text with ROT13 or a custom Caesar cipher shift. Letters shift, case and punctuation are preserved, all in your browser.
Shift every letter in your text forward (or backward) by a set number of places, from the classic ROT13 swap to any custom Caesar shift, useful for hiding spoilers, decoding old-school forum puzzles, or just seeing how these ciphers work.
How to use it
- Paste or type your text into the input box
- Set the shift amount (default 13 for classic ROT13, or choose your own 1-25)
- Copy the shifted output, or run it back through with the same shift to decode it
Frequently asked questions
- What's the difference between ROT13 and Caesar cipher?
- ROT13 is just a Caesar cipher locked to a shift of 13, which is why applying it twice gets you back to the original text. This tool lets you use that fixed shift of 13 or pick any shift from 1 to 25.
- Will it mangle numbers, spaces, or punctuation?
- No, only letters A-Z and a-z are shifted; digits, spaces, and symbols pass through untouched, and case is preserved.
- Is this secure enough to protect sensitive text?
- No, shift ciphers are trivial to break (there are only 25 possible shifts to try) so use this for puzzles, spoiler-hiding, or obfuscating text, not for actual secrecy.
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Nothing is uploaded
The file never leaves your device. There is no server to send it to, so there is nothing to leak, log, or subpoena.
- 2
No signup, no limits
No account, no email, no daily cap, no watermark, and no paid tier waiting behind the third file.
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Works offline
Load the page once and it keeps working with the network off, because all the work was always happening locally.