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Caesar Cipher

Encrypt or decrypt text with the classic Caesar shift cipher, using any shift value.

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How to use the Caesar Cipher

Choose Encrypt or Decrypt.
Set the shift amount (Caesar traditionally used 3).
Type your text — the result updates instantly.
Click Copy to grab the output. Letters shift; other characters stay the same.

Privacy: this tool runs entirely in your browser. Your input is never sent to, received by, or stored on any server — there are no uploads and no tracking of what you enter.

About Caesar Cipher

What is the Caesar cipher

One of the oldest ciphers, it shifts each letter a fixed number of places — Julius Caesar reputedly used a shift of 3. ROT13 is a Caesar cipher with shift 13.

How to use it

Choose encrypt or decrypt, set the shift, and type your text. Non-letters are left unchanged.

Security note

It provides no real security — there are only 25 possible shifts — but it's great for puzzles and learning.

Frequently asked questions

Is the Caesar cipher secure?

No — with only 25 shifts it's trivially broken. Use it for fun and learning.

What shift did Caesar use?

Traditionally 3.

How is it related to ROT13?

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