Regex Tester Online
Write regular expressions and test them against sample text in real time. See matches highlighted instantly as you type your pattern.
No account required - Start instantly
Debug Regular Expressions Without the Guesswork
Regular expressions are one of the most powerful tools in programming and one of the most frustrating to get right. A single misplaced quantifier or forgotten escape character can turn a pattern that should match email addresses into one that matches nothing or everything. Testing regex in your code means recompiling and rerunning after every tweak, which turns a five-minute task into a half-hour ordeal.
Our regex tester gives you a live feedback loop. Type your pattern in one field and your test text in another, and matches are highlighted immediately as you type. Every capture group, every match boundary, every flag is reflected in real time. You can see exactly what your pattern matches and what it misses without leaving the browser. When the highlighting is right, copy the pattern into your code with confidence.
The tester supports JavaScript, Python, and PCRE regex flavors so you can test with the same engine your code will use. Flags like global, case-insensitive, multiline, and dotall are toggled with a click. A built-in quick reference shows syntax for the most common constructs so you do not have to keep switching tabs to look up the syntax for lookaheads or named groups.
Complete Regex Testing
Everything you need to build patterns
Real-Time Matching
Matches highlight as you type. No button clicks, no delays, no recompilation.
Capture Group Display
See numbered and named capture groups with their matched content for each match.
Multiple Flavors
Test with JavaScript, Python, or PCRE engines to match your target runtime.
Flag Toggles
Enable global, case-insensitive, multiline, dotall, and unicode flags with a click.
Quick Reference
Built-in cheatsheet for character classes, quantifiers, anchors, and lookarounds.
Shareable Patterns
Save your regex and test text as a URL to share with teammates or bookmark.
How to Test Regular Expressions
Live feedback as you type
Enter Your Pattern
Type your regex pattern and select the appropriate flags and engine flavor.
Add Test Text
Paste or type the text you want to match against. Matches highlight instantly.
Refine and Copy
Adjust your pattern until the matches are correct, then copy it to your code.