ROT13 decoder, solver and encoder

ROT is a basic substitution cipher, where each letter is replaced by another letter 13 steps down the alphabet. It is a special case of the Caesar cipher. Since there are 26 letters (2 x 13) in the English alphabet, the shift direction does not matter and encoding is equivalent to decoding. ROT13 is used frequently in online forums to hide spoilers, puzzle solutions, etc from involuntary reading.

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  • The ROT13 is a very simple form of monoalphabetic substitution cipher.
  • ROT13 encryption is widely used forums to obfuscate text. It is equivalent to a Caesar cipher with a shift of 13.
  • To increase obfuscation, spaces can be removed or replaced with a character, such as X, in the plaintext before encryption.
  • A ROT13 provides no security in practise.

ROT13 is widely used in easy logic puzzles and to protect spoiler-text in forums from being read accidently.

Sample text


The ciphertext above represents "I CAME, I SAW, I CONQUERED." encrypted using ROT13.