🔡 ROT13
Encrypt and decrypt text with ROT13. Each letter is rotated 13 places (A becomes N, B becomes O, etc.). Encrypt equals decrypt.
About ROT13
ROT13 ("rotate by 13 places") is a special case of the Caesar cipher with a fixed shift of 13. Because the Latin alphabet has 26 letters, applying ROT13 twice returns the original text, so the same operation both encrypts and decrypts. It became popular on early internet forums and Usenet for hiding spoilers, punchlines, and potentially offensive content. This tool runs entirely in your browser — nothing is uploaded.
How it works
- Each letter is shifted 13 positions forward in the alphabet.
- A → N, B → O, ..., M → Z, and N → A, O → B, ..., Z → M.
- The same shift of 13 reverses the operation, so one button handles both encrypt and decrypt.
- Letter case is preserved; non-letter characters (digits, punctuation, spaces) are left unchanged.
Use cases
- Hiding spoilers, joke punchlines, or puzzle answers in forums and emails.
- Quick, reversible obfuscation that requires no key.
- Teaching the concept of self-inverse ciphers.
- Sanitizing potentially offensive text behind a one-step transformation.
Frequently asked questions
Is ROT13 secure? No. It provides no cryptographic security at all — anyone can read it by applying ROT13 again. Use it only for casual hiding, not for protection.
Why is there no mode selector? ROT13 is self-inverse: encoding and decoding use the same operation, so a single Execute button covers both.
Does ROT13 work on numbers? No. Only the letters A-Z and a-z are affected. Digits, punctuation, and other characters pass through unchanged.
Does this tool upload my text? No. All transformation happens locally in your browser.