Developer tool · Free · No sign-up
Regex Tester
Test, debug, and visualize regular expressions with instant match highlighting.
Regular Expression
Test String
Match Preview
Matches will appear here...Match Inspector
Enter a pattern and test string to see matches.
About this tool
This free Regex Tester allows you to test, debug, and visualize regular expressions directly in your browser. Enter your pattern, set your flags (like global or case-insensitive), and paste your test string to instantly see matches highlighted. It also extracts capture groups and provides clear error messages if your syntax is invalid. Everything runs locally on your machine—your data is never sent to a server.
Key features
Instant Match Highlighting
See exactly what your regex matches in real-time as you type.
Capture Group Inspection
Automatically extracts and displays all capture groups for every match found.
Flag Toggles
Easily toggle standard regex flags (g, i, m, s, u, y) with a single click.
How to use it
- 1Enter your regular expression pattern in the input box.
- 2Toggle any regex flags (like 'g' for global or 'i' for case-insensitive) you need.
- 3Paste or type the text you want to test against in the Test String area.
- 4View the highlighted matches in the preview area and inspect individual matches and capture groups on the right.
Common use cases
- Debugging a complex regular expression that isn't matching as expected.
- Extracting specific data (like emails or phone numbers) from a block of text.
- Learning how capture groups and regex flags behave in real time.
Frequently asked questions
Is my data sent to a server?
No. All regex parsing, matching, and highlighting happen entirely in your browser. Your text and patterns are never transmitted.
Which regex flags are supported?
You can easily toggle the standard JavaScript regex flags: g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode), and y (sticky).
Why is my regex showing an error?
If your pattern has invalid syntax (like an unmatched parenthesis), the tool will display a clear error message explaining the issue so you can fix it.
Private and free. Most of our tools run entirely in your browser, so the data you enter isn't uploaded or stored. There's no sign-up, and there never will be — they're built by the Fusion Trail Solutions team to be genuinely useful.
Need a custom tool or web app?
We design and build production-grade web apps, internal tools and SaaS platforms. Tell us what you need.
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