How do I decode ROT13?

Apply ROT13 again. Because the alphabet has 26 letters and the shift is 13, rotating twice returns to the start — encoding and decoding are literally the same operation.

No, and it never claimed to be. It hides text from accidental reading, nothing more. Anyone who recognises it can undo it in seconds.

The same rotation idea applied to 94 printable ASCII characters instead of 26 letters, with a shift of 47. Digits and punctuation are transformed too, which makes the output look far more scrambled — though it is equally trivial to reverse.

What is the difference from a Caesar cipher?

ROT13 is a Caesar cipher with the shift fixed at 13. A general Caesar cipher can use any shift from 1 to 25, which is why it needs brute-forcing and ROT13 does not.

ROT13 / ROT47 Decoder

Apply ROT13, ROT18 and ROT47 rotation ciphers — the same operation decodes and encodes.

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RAW INPUT

Mode

DECODED

Output appears here as you type — decoded on your device.

Input is processed on your device. Nothing you paste is sent anywhere.

What is the ROT13 / ROT47 Decoder?

ROT13 is a substitution cipher that replaces each letter with the one 13 places later in the alphabet, and because 13 is exactly half of 26, applying ROT13 a second time restores the original text.

ROT13 was never meant to be secure. It exists to hide text from casual reading — spoilers, punchlines, puzzle answers — on Usenet and in mailing lists, where the convention has survived for decades. Its charm is the self-inverse property: encoding and decoding are the same operation, so one function and one button do both jobs.

ROT47 extends the same idea across the printable ASCII range (characters 33 to 126), rotating by 47 so digits, punctuation and symbols shift too. It is likewise self-inverse. ROT18 is a hybrid that rotates letters by 13 and digits by 5, so 'a1' becomes 'n6'.

None of these are encryption, and nothing about them resists analysis — ROT13 is broken by reading it. They belong in the same category as pig latin: obfuscation with a well-known convention.