ROT13 Translator
Apply or reverse ROT13 instantly — the self-inverse letter cipher for hiding spoilers and puzzles. Optional ROT18 mode also rotates digits.
About the ROT13 Translator
ROT13 rotates every letter 13 places through the alphabet: A becomes N, B becomes O, and — because 13 is exactly half of 26 — running the result through ROT13 again restores the original. That self-inverse property made it the internet's traditional way to hide spoilers, puzzle answers and punchlines in plain sight since Usenet days.
This translator converts as you type, preserving case, spacing and punctuation, so encoding and decoding are the same single action — there is no direction to choose. A 'use result as input' button lets you verify the round trip, and the optional ROT18 mode additionally rotates digits by 5 (0 becomes 5, 1 becomes 6) for text that mixes letters and numbers.
ROT13 is obfuscation, not encryption — anyone with this page (or a minute of patience) can reverse it, which is precisely the point: it keeps text from being read accidentally while remaining trivially reversible. Everything happens in your browser with nothing uploaded.
How to Use the ROT13 Translator
- 1Type or paste your text — plain or ROT13-encoded, it doesn't matter.
- 2Read the converted result instantly; ROT13 encodes and decodes with the same operation.
- 3Enable the digits option (ROT18) if your text includes numbers to hide.
- 4Copy the result, or click 'use result as input' to round-trip it.
Frequently Asked Questions
Why does ROT13 both encode and decode with the same operation?
The alphabet has 26 letters and ROT13 shifts by exactly half of that. Shifting a letter 13 places twice moves it 26 places — right back where it started. So a single transform switches any text between plain and encoded forms; there's no key and no direction to remember.
What is ROT18 and when do I need it?
ROT18 combines ROT13 for letters with ROT5 for digits, mapping 0-4 to 5-9 and back. Enable the digits checkbox when your hidden text includes numbers — dates, scores, phone digits — since plain ROT13 leaves numbers readable.
Is ROT13 a form of encryption?
Technically it's a Caesar cipher with shift 13, but practically it's obfuscation: there's no key, and decoding requires no skill. It's meant to prevent accidental reading — spoilers, quiz answers, mildly rude jokes — not to protect secrets. Use modern encryption for anything sensitive.
What happens to punctuation, spaces and accented letters?
Only the 26 basic Latin letters (and digits, in ROT18 mode) are rotated. Spaces, punctuation, emoji and accented characters like é pass through unchanged, so the text's shape is preserved and decoding always restores the original exactly.
Where did ROT13 come from?
It became conventional on Usenet newsgroups in the early 1980s as a standard way to post spoilers and puzzle solutions that readers had to consciously decode. Many newsreaders even had a built-in ROT13 command — this page is the modern one-click equivalent.