ROT13 is a Caesar cipher with a shift of 13. Because the alphabet has 26 letters, applying ROT13 twice returns the original text, so the same operation both encodes and decodes.

Does it change numbers or symbols?

No. Only the letters a-z and A-Z are shifted (with wraparound). Digits, spaces, punctuation, and other characters are left exactly as they are.

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Caesar Cipher (ROT13)

Encode and decode with a letter shift.

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How to use the Caesar Cipher (ROT13)

1Paste or type your text into the input box.
2Set the shift amount (13 for ROT13) and pick Encode or Decode.
3Copy the converted result with one click.

About the Caesar Cipher (ROT13)

Free online Caesar cipher and ROT13 tool. Encode or decode text by shifting letters any amount, with instant output and one-click copy. No signup, runs in browser.

Part of our Text Tools collection. Browse all tools.

Frequently asked questions

What is ROT13?: ROT13 is a Caesar cipher with a shift of 13. Because the alphabet has 26 letters, applying ROT13 twice returns the original text, so the same operation both encodes and decodes.
Does it change numbers or symbols?: No. Only the letters a-z and A-Z are shifted (with wraparound). Digits, spaces, punctuation, and other characters are left exactly as they are.