Caesar Cipher
Encode or decode text with a Caesar shift cipher, including the classic ROT13.
Output
Only A-Z letters are shifted; ROT13 is its own inverse.
Private & SecureRuns in your browser — nothing is uploaded
Easy to UseJust paste or type — instant results
Free ForeverUnlimited use, no sign-up
Fast & ReliableAdvanced tech, fast and stable
A Caesar cipher shifts each letter a fixed number of places along the alphabet, the classic trick where A becomes D. This encodes and decodes text with the shift you choose. Everything runs in your browser, so your text never leaves your device.
How to use: Caesar Cipher
- 1Enter inputType your text.
- 2Set optionsSet the shift amount.
- 3ProcessUse ROT13 or shift 3 presets.
- 4Get resultCopy the result.
Common use cases
Make a simple puzzle or gameHide a clue or answer behind a letter shift for a game or an escape room.
Decode a Caesar messageRecover text someone shifted, once you know or guess the amount.
Teach how ciphers workShow how a shift cipher encodes and decodes, step by step.
Lightly obscure a spoilerScramble a punchline or spoiler so it's not readable at a glance.
Good to know
It's a toy, not securityA Caesar cipher is trivial to break and is not real encryption, so never use it to protect anything sensitive like passwords or private messages.
Only letters shiftNumbers, spaces and punctuation usually pass through unchanged, which can leak the shape of the message.
You need the shift to decodeDecoding needs the same shift used to encode; if you don't know it, there are only 25 to try, which is exactly why it's not secure.