ROT13
ROT13. A classical cipher, computed on your device.
Runs on your device. The file is never uploaded.
ROT13 rotates every letter of a text file 13 places through the alphabet and prints the result. Case survives the mapping, and digits, punctuation and non-Latin letters are passed over untouched. The options schema is empty, so there is nothing to set and nothing to keep, which also means anyone can reverse it in one run.
Questions
Is ROT13 encryption?
No. It is a fixed letter rotation with no key at all, used to hide spoilers and punchlines from a casual glance. Anyone can undo it instantly, including this page. It protects nothing and was never meant to. For actual protection use AES-GCM encrypt.
How do I undo it?
Run the same tool again on the output. ROT13 shifts every letter 13 places and the alphabet has 26, so applying it twice returns the original text exactly, including case, spacing and punctuation. There is no separate decode tool and no setting to get wrong, which is the main reason to use this rather than Caesar encode with a shift of 13.
Are there any options?
None. It takes a file and returns the rotated text, and the result is the same every time for the same input. If you want a different shift, use Caesar encode, which takes a shift from 1 to 25; a shift of 13 there gives exactly this result.
What happens to digits and symbols?
They are unchanged. Only A to Z and a to z rotate, and case is preserved. If you also want digits rotated, ROT5 (digits) on this site does that part, and ROT47 covers a wider range of printable ASCII instead.
Where does my text go?
Nowhere. The rotation happens in a Web Worker in this tab and the result is shown on the page. Nothing is uploaded, nothing is stored between runs, and the site works with the network off. That is true of every tool here, and it is the only protection ROT13 text gets, since the cipher provides none.