Caesar / ROT13

What it's for

Shift every letter a fixed number of places along the alphabet, the cipher Julius Caesar used, or apply one of the ROT variants. ROT13 is the shift of 13 that hides spoilers and puzzle answers, since doing it twice gives back the original.

For example, when a puzzle or geocache gives you a line of scrambled letters, paste it in and look at the list of every shift: the one that reads as English is at the top.

How to use it

Type or paste text and the result appears as you type. For Caesar, choose the shift and whether to encrypt (shift forward) or decrypt (shift back); the cipher and shift are remembered. ROT5 shifts only digits, ROT18 does ROT13 and ROT5 together, and ROT47 rotates every printable ASCII character, so punctuation changes too.

Every shift lists all 25 Caesar shifts of your text, ranked by how much each looks like English, with the best marked. Choose a shift’s name to use it above; each has a Copy button.

Example

Paste this into Text:

Wkh txlfn eurzq ira

Every shift puts Shift 23 — best at the top, reading The quick brown fox. Shifting forward 23 is the same as shifting back 3, Caesar’s own key.

Good to know

Only the letters A to Z shift; accented letters, digits (except in ROT5 and ROT18) and punctuation are left as they are. The ranking judges letter frequencies and common words, so very short text can rank a wrong shift first. A Caesar shift is a puzzle, not protection: anyone can undo it in seconds.