Regex Tester
Test regular expressions live with match highlighting and capture groups.
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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.