Regex Tester
Test and debug regular expressions live with match highlighting, capture groups, and all flags (g, i, m, s, u, y). Runs entirely in your browser.
Popular in this group
Switch tools without re-entering your text.
Loading tool…
About this tool
Regex Tester — The Regex Tester lets you build and debug regular expressions and see what they match in real time. Enter a pattern, toggle the flags you need (global, ignore-case, multiline, dotall, unicode, sticky), and paste a test string — matches are highlighted in place and listed below with their capture groups and a total count.
It uses your browser's own regular-expression engine (the same one your JavaScript runs), so behavior matches what you will get in code. Invalid patterns show a clear error instead of failing silently, and nothing you type is uploaded.
How to use it
- Type your regular expression in the pattern field.
- Turn on the flags you need, such as g or i.
- Paste your test text and read the highlighted matches and groups.
Frequently Asked Questions
Which regex syntax is this?+
It is JavaScript (ECMAScript) regular-expression syntax, since the test runs with the browser engine.
What do the flags mean?+
g matches all occurrences, i ignores case, m makes ^ and $ work per line, s lets the dot match newlines, u enables full unicode, and y anchors at lastIndex.
Can it see my text?+
No. Matching runs entirely in your browser.