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ROT13 / Caesar Cipher

Apply a Caesar shift to text. ROT13 is the famous self-inverse version. Useful for puzzles, spoilers, light obfuscation.

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How to use ROT13 / Caesar Cipher

  1. Paste your text.
  2. Set the shift value (or click ROT13 for the classic 13).
  3. Copy the result.

What is ROT13 / Caesar Cipher?

The Caesar cipher is one of the oldest known ciphers, dating to Julius Caesar's correspondence. It shifts each letter forward or backward by a fixed amount in the alphabet. ROT13 — a shift of 13 — is self-inverse and widely used to hide minor spoilers in online discussions.

This is not real encryption. Don't use it for anything sensitive.

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FAQ

Why is ROT13 special?
Applying ROT13 twice returns the original text — it's self-inverse — so the same tool both encodes and decodes.
Is this real encryption?
No. Caesar ciphers are trivially reversible and meant for puzzles, spoilers, or light obfuscation — never for protecting sensitive data.
Does my text get sent to a server?
No — all shifting is done locally in your browser. Your text never leaves your device.

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Author

NK
Prof. Noah Klein"The Privacy Guardian"

Cybersecurity Researcher & Privacy Advocate

Professor Klein holds a PhD in Information Security and has testified before EU parliamentary committees on data privacy legislation. He builds encryption tools for journalists, audits web applications for security flaws, and believes that privacy is not a feature but a fundamental right. His research has been cited in Wired, Nature, and The Guardian, and he advises nonprofits on responsible data stewardship.

📖 ROT13 / Caesar Cipher on Wikipedia·Encoding on Wikipedia·ROT13 / Caesar Cipher on Britannica

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