Test regex patterns without leaving the browser workspace
Validate JavaScript regular expressions, inspect match positions, review capture groups, and preview replacements in one fast editor.
Live count from the current regex
JavaScript RegExp flags in use
Matches browser JavaScript regex behavior
Pattern
Build and test the regex
Match preview
See the match regions live
user_id=42 email=hello@example.com status=200
user_id=108 email=team@mtkits.com status=404
user_id=777 email=support@site.dev status=500
Replace preview
Test the replacement result
Match list
Inspect matches and capture groups
Match 1
Index 29
No capture groups returned for this match.
Match 2
Index 76
No capture groups returned for this match.
Match 3
Index 121
No capture groups returned for this match.
How it works
A focused regex workflow instead of scattered checks
Enter the pattern
Paste a regular expression body without the surrounding slashes so you can edit it directly.
Toggle the flags
Switch on the exact regex flags you need and watch the result update live.
Inspect or replace
Review match positions, capture groups, and replacement output in the same workspace.
FAQ
Regex details that usually trip people up
Does this regex tester support capture groups?
Yes. Each match card lists the captured groups so you can verify group ordering and replacement references quickly.
Why does the replace preview only change the first match sometimes?
That is standard JavaScript regex behavior. If you want all matches replaced, enable the global g flag.
Which regex engine does this tool follow?
This tester uses the browser’s JavaScript RegExp engine, so the syntax and flags match what you would expect in JavaScript-based tooling.
Share this regex tool
This route now has its own Open Graph and Twitter metadata, so shares can show a dedicated preview instead of generic site copy.
Next steps