How rot13 encoder & decoder works
ROT13 ('rotate by 13 places') is a Caesar cipher with a fixed shift of 13. Because the English alphabet has 26 letters, shifting by 13 twice returns the original text, so the exact same operation both encodes and decodes — there is no separate decrypt step. A becomes N, B becomes O, M becomes Z, and N wraps back to A.
The tool shifts only letters, preserving upper and lower case, and leaves digits, punctuation, spaces, and other characters untouched. ROT13 is not encryption: it provides no confidentiality and is trivially reversed, so it is used only to obscure text in plain sight.
ROT13's most common use is hiding spoilers, punchlines, and answers online (newsgroups, forums, puzzle sites) so a reader has to deliberately decode it before reading the content. It is also a classic teaching example for substitution ciphers and frequency analysis. All processing happens in your browser.