Regex Tester
//g
Flags:
1
2
3
The quick brown fox jumps over the lazy dog.
Pack my box with five dozen liquor jugs.
How vexingly quick daft zebras jump!
Online Regular Expression Tester
io9.me Regex Tester lets you write and test JavaScript regular expressions with instant visual feedback. Type a pattern and test string, and matches are highlighted in real time. Capture groups are extracted and displayed alongside each match.
Features
- Live matching — see results instantly as you type the pattern or test string
- Capture groups — view numbered and named groups for every match
- All JavaScript flags — global (g), case-insensitive (i), multiline (m), dotAll (s), unicode (u), sticky (y)
- Color-coded match highlighting in the test string
- Quick-reference cheatsheet for regex syntax
- Replace mode to test substitution patterns
How to use
- Enter a regex pattern in the pattern field.
- Toggle flags (g, i, m, etc.) as needed.
- Paste or type your test string below.
- Matches are highlighted in real time; capture groups appear in the results panel.
Common regex patterns
- Email validation: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}
- URL matching: https?:\/\/[^\s]+
- IP address: \b\d{1,3}(\.\d{1,3}){3}\b
- Date (YYYY-MM-DD): \d{4}-\d{2}-\d{2}