ROT13 Encoder / Decoder
Encode or decode text with the ROT13 cipher. Self-inverse: same button encodes and decodes.
ROT13 Encoder / Decoder
Apply the ROT13 substitution cipher to any text. ROT13 is self-inverse — encoding and decoding use the same operation.
Input
Output (ROT13)
Encoded text will appear here…What is ROT13?
ROT13 ("Rotate by 13") is a simple letter-substitution cipher that replaces each letter with the 13th letter after it in the Latin alphabet. Because the alphabet has 26 letters, applying ROT13 twice returns the original text — making it self-inverse. It is commonly used to hide spoilers and puzzle answers on the internet.
FAQ
Is ROT13 encryption?▼
No. ROT13 is a trivial substitution cipher with zero cryptographic security. Never use it to protect sensitive data.
Does ROT13 affect numbers or punctuation?▼
No. Only the 26 Latin letters (A–Z, a–z) are rotated. Numbers, spaces, and punctuation are left unchanged.
How do I decode a ROT13 message?▼
Apply ROT13 again. Because 13+13=26 (full alphabet), encoding and decoding are identical operations.
Frequently Asked Questions
What is ROT13?
ROT13 is a simple letter substitution cipher that replaces each letter with the letter 13 positions after it in the Latin alphabet. ROT13 is its own inverse: applying it twice returns the original text.
Is ROT13 secure encryption?
No. ROT13 provides zero security. It is only used to obscure text from casual readers (e.g., spoilers, puzzle answers) — not to protect sensitive information.
What is the difference between ROT13 and Caesar cipher?
ROT13 is a specific case of the Caesar cipher with a shift of 13. Because 13 is exactly half of 26 letters, ROT13 is its own inverse, making encode and decode identical operations.