Home › Utility & Security Tools › ROT13 Encoder / Decoder
Apply ROT13 to any text — the same operation encodes and decodes since ROT13 is its own inverse. Instant, live transformation as you type.
ROT13 Encoder · works in real-time entirely client-side · 100% private
Enter the message you want to encode or decode — it’s the same operation either way.
Click encode/decode (or see it update live) — each letter shifts 13 positions in the alphabet, wrapping around.
The transformed text is ready to copy. Apply ROT13 again to reverse it.
ROT13 (Rotate by 13) is a letter substitution cipher that shifts each letter 13 positions forward in the English alphabet. A becomes N, B becomes O, and so on. Because the English alphabet has 26 letters, applying ROT13 twice returns the original text — making the same function both encoder and decoder. It’s a special case of the Caesar cipher with a fixed shift of 13.
ROT13 is used to obscure text without hiding it completely — it requires a deliberate decode step but is trivial to reverse. Common uses include: hiding spoilers in online discussions so readers must actively choose to see them, obfuscating punchlines or puzzle answers, and as a trivial encoding example in programming exercises. It is not secure encryption.
Standard ROT13 shifts only the 26 letters of the English alphabet — uppercase and lowercase independently. Numbers, punctuation, spaces, and non-Latin characters are passed through unchanged. ROT47 is an extended variant that also rotates printable ASCII characters including digits and punctuation, covering a wider character range.
No. ROT13 transformation runs entirely in your browser. Text is never transmitted to any server.
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ROT13 is the internet’s classic light-obfuscation tool — used in Usenet groups since the 1980s and still common in online communities for hiding spoilers, puzzle answers, and punchlines. The elegant property that the same operation encodes and decodes (because 13+13=26) makes it trivially reversible, which is exactly the point: the barrier is intentional, not cryptographic. This tool applies ROT13 instantly to any text, updating live as you type, and covers the standard letters-only transformation as well as ROT47 for ASCII-extended encoding.
All transformation runs in your browser. Text is never uploaded or transmitted to any server.