Regex Tester
Live matches, highlighting and capture groups.
About Regex Tester
Regex Tester runs a pattern against sample text with live highlighting, a match count and every capture group listed. Flags are toggled individually with explanations, which removes the usual guesswork about whether you need g, m or s.
How to use it
- Type your pattern, without the surrounding slashes.
- Toggle the flags you need.
- Paste test text — matches highlight as you type, with capture groups listed below.
Questions
What do the flags mean?
g finds all matches rather than stopping at the first; i ignores case; m makes ^ and $ match each line; s lets . match newlines; u enables full Unicode handling.
Which flavour of regex is this?
JavaScript’s. Most syntax is shared across languages, but lookbehind, named groups and Unicode property escapes vary — test in your target language before relying on them.
Why does my pattern match nothing?
Most often unescaped special characters. In regex . matches any character, so to match a literal full stop you need \. — the same applies to ? + * ( ) [ ] { } | ^ $.
Regex Tester is free and runs entirely in your browser. No account, no upload, no watermark, no limit on use.