JavaScript's native RegExp engine. Most syntax is shared with PCRE (PHP, Python), but always verify critical patterns in your deployment language.
Free Developer Tool
Regex Tester
Test regular expressions live against your text — matches highlight
instantly, capture groups break out into a table, and a replace mode
previews substitutions with $1-style references.
- ✔ Live match highlighting
- ✔ Capture group breakdown
- ✔ Replace mode preview
- ✔ Common pattern library
- ✔ Free Forever
Test Regular Expressions in Real Time
Regular expressions are precise but unforgiving — a single misplaced character can silently change what a pattern matches, and debugging that by staring at code is slow. This tool runs your pattern against real text as you type, highlights every match inline, breaks out numbered and named capture groups into a table, and lets you preview a replacement before you commit it to actual code.
How It Works
1. Enter a Pattern
Type your regex and toggle flags (g, i, m, s, u, y).
2. Paste Test Text
Matches highlight instantly as you type either field.
3. Review Matches
See every match, its index, and capture groups in a table.
4. Test Replacement
Switch to Replace mode to preview substitutions live.
/
/
gi
Uses the same pattern and flags from the Test & Match tab. Use
$1, $2 etc. to reference capture groups, or
$<name> for named groups.
| Syntax | Meaning | Category |
|---|
FAQsRegex Tester
What regex flavor does this tool use?
What is the difference between greedy and lazy quantifiers?
Greedy (* or +) matches as much as possible. Lazy (*? or +?) matches as little as possible — important when matching between delimiters to avoid overshooting.