Caesar Cipher Decoder

Crack a Caesar cipher in seconds by seeing every possible shift side by side, or encode your own secret message.

How to use the Caesar Cipher Decoder

  1. Type or paste your text into the box on the left.
  2. Adjust the options above if you need to. The result updates as you type.
  3. Click Copy result or Download to use your result.

What you can use it for

  • Crack cipher puzzles and CTF challenges
  • Teach basic cryptography
  • Write secret notes

Private by design

The Caesar Cipher Decoder runs entirely in your browser. Your text and files are never uploaded or stored on a server, so it is safe for work documents and personal information. It is free, with no sign-up and no limits on how often you use it.

Frequently asked questions

How do I decode without knowing the shift?

Choose "Try all 25 shifts" and look for the line that reads as normal words.

Is ROT13 a Caesar cipher?

Yes. ROT13 is a Caesar cipher with a shift of 13.

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