ROT13 Encoder/Decoder

Shift every letter 13 places — the same operation encodes and decodes.

A free online ROT13 encoder/decoder — paste any text and every letter shifts 13 places through the alphabet instantly. Since the alphabet has 26 letters, running it twice returns the original — there's no separate encode/decode mode. No signup, runs entirely in your browser.

Examples:

Input

ROT13 Output

What is ROT13?

ROT13 ("rotate by 13") is the simplest possible letter-substitution cipher — every letter is replaced with the one 13 places later in the alphabet, wrapping around at the end (A↔N, B↔O, C↔P, and so on). Because the English alphabet has exactly 26 letters, shifting by 13 twice lands back on the original letter, which is why ROT13 is its own inverse: the same transform both encodes and decodes. It's commonly used on forums and puzzle sites to hide spoilers, answers, or mildly offensive text from a casual glance — never for anything that needs real security.

Example: encoding and decoding

Paste Hello, World! and you get Uryyb, Jbeyq! back. Paste that result in again (click "Use as input" to do it in one click) and you're back to Hello, World! — there's no encode/decode toggle because ROT13 doesn't need one.

ROT13 is not encryption

ROT13 has no secret key — anyone who recognizes the pattern (or just runs it through this tool) can reverse it instantly. It's a convention for hiding text from a casual glance, not a security measure. Never use ROT13 to protect passwords, personal data, or anything that actually needs to stay confidential.

What stays unchanged

Only the 52 letters A-Z and a-z are shifted. Numbers, spaces, punctuation, emoji, and non-Latin characters pass straight through untouched, and uppercase letters stay uppercase after the shift (an uppercase "H" becomes an uppercase "U", not lowercase).

Frequently asked questions

ROT13 ("rotate by 13") is a simple letter-substitution cipher that shifts every letter 13 places through the alphabet — A becomes N, B becomes O, and so on. Because the alphabet has 26 letters, applying ROT13 twice returns the original text, so the same operation both encodes and decodes.

Paste the ROT13 text into the input — the decoded result appears instantly. There's no separate decode mode: running ROT13 on ROT13'd text returns the original.

No — ROT13 provides no real security. It has no key and is trivial to reverse by anyone who recognizes it. It's traditionally used to hide spoilers, puzzle answers, or offensive text from casual view, not to protect genuinely sensitive information.

Only letters A-Z and a-z are shifted. Numbers, spaces, punctuation, and any other characters pass through completely unchanged, and letter case is preserved (uppercase stays uppercase).

No. The transform happens locally in your browser with JavaScript — nothing you type is ever sent anywhere.

Related tools: Base64 Converter · Morse Code Translator · Hex Decode