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ROT13 Encoder / Decoder

Apply ROT13 (or any custom Caesar cipher rotation) to your text. ROT13 is its own inverse — encoding and decoding use the same operation. Non-letter characters are passed through unchanged.

Rotation: ROT13
Plain Text 0 chars
ROT13 Output 0 chars
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📖 ROT13 Reference
A↔N   B↔O   C↔P
D↔Q   E↔R   F↔S
G↔T   H↔U   I↔V
J↔W   K↔X   L↔Y
M↔Z
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What is ROT13?

ROT13 (Rotate by 13) is a simple letter substitution cipher that replaces each letter with the letter 13 positions after it in the alphabet. Since the English alphabet has 26 letters, applying ROT13 twice returns the original text — encoding and decoding are the same operation. ROT13 was commonly used in Usenet groups and early internet forums to obscure spoilers, solutions to puzzles, or potentially offensive content.

Frequently Asked Questions

No. ROT13 is a trivial substitution cipher with no key — anyone who knows ROT13 (which is common knowledge) can instantly decode it. It provides zero security and should never be used to protect sensitive information. Its only purpose is to mildly obscure text from casual reading, like hiding a movie spoiler.
ROT13 is a specific Caesar cipher with a fixed rotation of 13. A Caesar cipher uses any rotation from 1 to 25. Julius Caesar reportedly used ROT3 (shift of 3) for his military communications. This tool supports all 25 rotations via the custom shift option.
ROT13 is defined as operating only on the 52 Latin letters (A–Z, a–z). Numbers, punctuation, spaces, and other characters are passed through unchanged. This preserves the readability of non-alphabetic content while obscuring the letter-based meaning.
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Frequently Asked Questions

Is this ROT13 Encoder / Decoder free to use? +
Yes, completely free. No signup, no account, no payment required. Just paste your input and use it directly in your browser.
Does this tool store or send my data anywhere? +
No. Everything runs entirely in your browser using JavaScript. Your data never leaves your device or gets sent to any server.
What browsers does this tool support? +
It works in all modern browsers — Chrome, Firefox, Safari, Edge, and Opera — on both desktop and mobile.
Can I use this tool offline? +
Once the page is loaded, the tool runs locally in your browser without needing an active internet connection for most operations.
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This ROT13 Encoder / Decoder works for most use cases — but if you need batch processing, API access, private hosting on your own domain, or a completely bespoke tool built around your workflow, I can build it.

Request Custom Build → Typical turnaround: 3–7 days