Decoder reads a regular expression and explains it in plain words, piece by piece, so you can understand what an unfamiliar pattern actually matches. Paste a regex, and each token is broken out and described. Nothing is uploaded.

Regular expression

Breakdown

Test a string against it

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Decoder recognises the common regular-expression syntax — anchors, quantifiers, character classes, groups, escapes and alternation. Very advanced constructs like look-behind or recursion may be described only loosely. The test box uses your browser's own regex engine (JavaScript). Everything runs on your device.