ROT13 Encoder/Decoder
Encode or decode ROT13 text instantly — the classic Caesar substitution cipher that is its own inverse. Free, client-side ROT13 cipher translator.
🔒 100% Client-Side Processing
Your data is processed entirely in your browser and never transmitted to any server.
0 / 100M Limit
Common Use Cases
Hiding spoilers and answers
Encode plot spoilers, puzzle solutions, and quiz answers so readers only decode them deliberately.
Decoding Usenet-era text
Read ROT13-encoded content from forums, old archives, and geocaching hints that still use the convention.
Teaching classical ciphers
Demonstrate substitution ciphers and why they offer no real security, with instant encode/decode.
Frequently Asked Questions
- How does ROT13 work?
- Each letter is replaced by the letter 13 positions later in the alphabet, wrapping around — A→N, B→O, N→A. Because 13 is half of 26, applying ROT13 twice restores the original, so encoding and decoding are the same operation.
- Is ROT13 secure?
- Not at all — it is a fixed substitution with no key, trivially reversed by anyone. Its legitimate uses are hiding spoilers and puzzle answers from casual glances, and historic Usenet convention. For real secrecy use actual encryption.
- Is my data private when I use this tool?
- Yes. This tool runs entirely in your browser using client-side JavaScript — nothing you type is transmitted to, logged by, or stored on any server. You can safely process confidential text, tokens, or code.