How to use ROT13 / Caesar
- Add or paste your input above.
- Click the action button to run ROT13 / Caesar.
- Copy or download your result.
About ROT13 and Caesar ciphers
ROT13 is a simple letter-substitution cipher that rotates each letter 13 places through the alphabet — applying it twice returns the original text. A Caesar cipher does the same with any shift amount. Both are classic teaching tools and are used to hide spoilers and puzzle answers.
Tips
- ROT13 is its own inverse — encode and decode use the same step.
- Adjust the shift for a general Caesar cipher.
- These ciphers are for fun and learning, not real security.
ROT13 / Caesar — frequently asked questions
- Is ROT13 secure?
- No. ROT13 and Caesar ciphers offer no real protection and are trivial to reverse. They are meant for puzzles and obscuring spoilers, not security.
- Is ROT13 / Caesar free to use?
- Yes. ROT13 / Caesar is completely free with no sign-up, no watermarks and no usage limits.
- Is my data uploaded to a server?
- No. ROT13 / Caesar runs entirely in your browser, so your data never leaves your device.
- Is there a size limit?
- Only your device's available memory — there are no server-side limits because nothing is uploaded.