ROT13 / Caesar Cipher

Rotate letters by 13 or any shift — the classic cipher for spoilers, puzzles and puzzles’ answers.

About this tool

ROT13 replaces each letter with the one 13 positions later — applying it twice returns the original text, which made it the traditional way to hide spoilers and puzzle answers. This tool also supports every other Caesar shift (0–25) so you can encode and decode classic shift ciphers in both directions.

How to use it

  1. Type or paste your text, or click Sample.
  2. Set the shift (13 gives classic ROT13) and click Shift ▸; use ◂ Unshift to reverse any shift.

Good to know

  • Letter case is preserved; digits, punctuation and accented characters pass through unchanged.
  • Caesar/ROT13 offers no real security — it is obfuscation for puzzles and spoilers only.
  • With shift 13, encoding and decoding are the same operation.