What it does
This tool bundles the whole family of ROT ("rotate") ciphers into a single encoder/decoder:
| Variant | What it rotates | Alphabet size | Notes |
|---|---|---|---|
| ROT1 | Letters A-Z / a-z | 26 | Shifts every letter by 1 position |
| ROT5 | Digits 0-9 | 10 | Shifts only numbers by 5; leaves letters untouched |
| ROT13 | Letters A-Z / a-z | 26 | The classic — shift by 13, so it's its own inverse |
| ROT18 | Letters + digits | 26 + 10 | ROT13 (letters) + ROT5 (digits) combined |
| ROT47 | Printable ASCII 33–126 | 94 | Covers letters, digits, and symbols; its own inverse |
| ROT8000 | Unicode "meme" mapping | — | A joke cipher mapping common words/characters to emoji — not reversible in the mathematical sense, but this tool provides a matching decoder for the same table |
All of them are simple substitution ciphers with no real cryptographic security — they're used for obfuscating spoilers, puzzle hunts, forum jokes, and CTF warm-ups, not for protecting sensitive data.
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How it works
ROT1
Every letter is shifted by 1 position in the alphabet, wrapping around from z back to a (and Z back to A). Non-letters are left as-is. Encoding and decoding use opposite shift directions (+1 / -1).
ROT5
Every digit 0-9 is shifted by 5 positions, wrapping around (0 → 5, 7 → 2, etc). Letters and symbols are untouched. Because 5 is exactly half of 10, ROT5 is its own inverse — running it twice returns the original text.
ROT13
The classic: every letter is shifted by 13 positions. Since the Latin alphabet has 26 letters and 13 is exactly half, ROT13 is its own inverse — applying it twice returns the original text. This is why ROT13 famously has a single "Apply ROT13" button on many implementations instead of separate encode/decode.
ROT18
Simply ROT13 applied to letters combined with ROT5 applied to digits, in a single pass. Also its own inverse, for the same reason as above (13 = half of 26, 5 = half of 10).
ROT47
Instead of only the 26-letter alphabet, ROT47 rotates across the 94 printable ASCII characters from ! (33) to ~ (126). This means digits, punctuation, and symbols get scrambled too, not just letters. Since 94 is even and 47 is exactly half, ROT47 is also its own inverse.
ROT8000
A tongue-in-cheek "extension" of the ROT joke format that maps common letters/short words to emoji instead of rotating within an alphabet. It isn't a mathematical rotation and there's no universally standardized mapping — this tool implements a small, self-consistent word/letter-to-emoji table so that encoding and then decoding with the same tool round-trips correctly. Treat it as pure fun, not as an interoperable standard.
Why these are reversible with one shift value
For ROT13/ROT18/ROT47/ROT5, the rotation amount is exactly half the alphabet size being used. Rotating by half the alphabet twice brings you back to a full rotation (i.e., back to the start), which is why the same operation both encodes and decodes. ROT1 does not have this property (shifting by 1 twice does not undo itself), so this tool applies a genuine inverse shift (-1) when you click "Decode".
Security notice
None of these ciphers provide real security. They have no secret key (or a trivial/fixed one) and can be broken instantly by frequency analysis or simply trying the fixed shift. Use them for fun, obfuscating spoilers, or puzzle/CTF purposes only — never for protecting real secrets.