Caesar Cipher / ROT13 Encoder & Decoder
Shift letters by a fixed amount to encode or decode. ROT13 is shift-13 — one click away.
About this tool
One of the oldest ciphers: shift every letter forward by a fixed amount, wrapping from z back to a. ROT13 is the special case where shift=13 (encode and decode are the same operation).
Cracking an unknown shift
Only 25 possible shifts — ‘Show all 25 shifts’ tries every one so you can spot the readable result. Nothing is uploaded.