Regex Tester
This regex tester lets you write a regular expression, toggle flags, and see every match highlighted in your sample text as you type. Capture groups are listed separately with their match offsets, so you can confirm exactly what each group captures. It uses the same regex flavor built into modern web browsers and runs entirely client-side, with no text sent anywhere.
Emails: alice@example.com, bob@example.org, no-match
Match details
- #1 @ 8: alice@example.com — groups: ["alice", "example.com"]
- #2 @ 27: bob@example.org — groups: ["bob", "example.org"]
Frequently asked questions
Which regex flavor does this tester use?
It uses the standard regular-expression flavor built into modern web browsers, so patterns behave the same way they will in your browser-based code.
Which regex flags are supported?
All six standard flags are supported: g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode), and y (sticky).
How do I see what a capture group matched?
Capture groups are listed below the match results with their position offsets, so you can check each group’s captured text without writing extra code.
Why isn’t my regex matching anything?
Common causes are a missing global flag when you expect multiple matches, unescaped special characters like "." or "(", or a pattern anchored with "^" or "$" against multiline text without the multiline flag enabled.
Is my test text or pattern sent to a server?
No. Matching runs entirely in your browser as you type — neither the pattern nor the sample text is uploaded.