Free Online Regex Tester
Enter a regular expression and test it against live text in your browser. Matches and capture groups are highlighted in real time, with no data sent to BuBird servers.
✓ Free developer tool✓ No account required✓ Browser-based utility✓ Fast results✓ Mobile friendly
Regex Pattern
Flags
Test String
This tool runs in your browser and does not upload your data to BuBird servers.
How To Use
How to Use Regex Tester
1
Enter Your Pattern
Type or paste your regular expression into the pattern field. Include flags (g, i, m) as needed.
2
Paste Test Text
Enter the text you want to test against your pattern in the test string area.
3
See Live Matches
Matches are highlighted in the test text immediately. Capture groups and match details appear in the results panel.
4
Refine the Pattern
Edit the regex or the test text and watch results update in real time until your pattern behaves as expected.
Example
Example Use
Validating Email Addresses
Use the pattern ^[\w.+-]+@[\w-]+\.[a-zA-Z]{2,}$ with the global flag to test a list of email addresses. Matching lines are highlighted green so you can immediately see which addresses pass validation and which do not.
Use Cases
Who Uses Regex Tester
Developers
Build and test input validation patterns for forms, APIs, and data parsing before adding them to code.
Data Engineers
Test extraction patterns to pull specific fields from logs, CSV, or structured text files.
QA Engineers
Verify that test data matches or excludes expected patterns during automated testing setup.
Students & Learners
Explore how regex syntax works by testing patterns against real text and seeing instant visual feedback.
Technical Writers
Use regex patterns to find and standardise inconsistent formatting in documentation drafts.
Security Researchers
Test patterns for identifying specific strings, IP addresses, or patterns in log analysis.
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FAQ
Frequently Asked Questions
What regex flavour does this tester use?
The tester uses JavaScript (ECMAScript) regular expressions, which are supported natively in all modern browsers. Most patterns are portable to other languages with minor syntax differences.
Can I use flags like global, case-insensitive, or multiline?
Yes. You can set flags such as g (global), i (case-insensitive), m (multiline), and s (dotAll) using the flag input in the tool.
Does the tool show capture groups?
Yes. Named and numbered capture groups are shown in the match results so you can inspect exactly what each group captures from the test text.
Is my test text sent to any server?
No. Regex matching runs entirely in your browser using JavaScript. Your pattern and test text never leave your device and are not sent to BuBird servers.
Can I use this to test email or URL validation patterns?
Yes. Paste your email, URL, or any validation regex into the pattern field and test it against example inputs to see which strings match and which do not.