Which regex flavours are supported?

The explainer uses JavaScript regex syntax, which closely matches the syntax used in Python, Java, and most modern languages for common patterns.

Does it explain lookaheads and lookbehinds?

Yes. (?=...) positive lookaheads, (?!...) negative lookaheads, and lookbehind assertions are explained in plain English.

Can I test my regex against a sample string?

Yes. Paste a test string and the tool highlights all matches and shows which capture groups matched what.

Best Free Regex to English Explainer

Regular expressions are powerful but notoriously hard to read, especially patterns written by someone else or inherited from legacy code. devtoolkit.sh's Regex Explainer parses any regex and breaks it down into a plain English description of what each part does — groups, quantifiers, character classes, anchors, and lookaheads are all explained clearly. It also highlights which parts of a test string are matched by each component, making it easy to verify the pattern's behaviour. Everything runs in your browser without sending any data to a server. This is invaluable for code reviews, learning regex syntax, debugging patterns that are almost-but-not-quite right, and documenting regular expressions for other developers.

Regex pattern

FAQ

Which regex flavours are supported?: The explainer uses JavaScript regex syntax, which closely matches the syntax used in Python, Java, and most modern languages for common patterns.
Does it explain lookaheads and lookbehinds?: Yes. (?=...) positive lookaheads, (?!...) negative lookaheads, and lookbehind assertions are explained in plain English.
Can I test my regex against a sample string?: Yes. Paste a test string and the tool highlights all matches and shows which capture groups matched what.