How to use
- Type or paste your text.
- Set the shift (13 = ROT13) and whether to decode.
- Copy the transformed text.
About this tool
Shift every letter along the alphabet by a fixed amount — the classic Caesar cipher. Leave the shift at 13 for ROT13, the self-reversing encoding used to hide spoilers and puzzle answers. Free online text tools. Everything runs in your browser — your text never leaves your device.
FAQ
What is ROT13?
A Caesar cipher with a shift of 13. Because the alphabet has 26 letters, applying it twice returns the original text, so the same setting both encodes and decodes.
What happens to numbers and punctuation?
Only A–Z and a–z are shifted; digits, spaces, and punctuation pass through unchanged. Letter case is preserved.
Is a Caesar cipher secure?
No — it is trivially broken and is meant for fun, puzzles, and lightly obscuring text (like spoilers), not real security.