Ways to use Regex Tester
Test a JavaScript pattern against real text
Try a regular expression, inspect every match and capture group, and move structured captures into another tool.
Develop a JavaScript pattern
Edit a pattern and flags while seeing which parts of the test text match.
Inspect capture groups
Review each match, its index, and named or numbered captures in a table.
Prepare captured data
Send captures to JSON Wizard or CSV / JSON Converter, or copy all full matches as separate lines.
How to use it
- Enter a JavaScript regular-expression pattern without the surrounding slashes.
- Choose flags and paste the text you want to test.
- Navigate highlighted matches, then inspect, copy, or convert the results.
Understand the result
- Flags
- Use g, i, m, s, u, or y to control global, case-insensitive, multiline, dot-all, Unicode, or sticky matching.
- Match navigation
- The counter and arrow controls move through highlighted matches in source order.
- Capture groups
- The match table shows full matches, indices, and named or numbered captured values.
- Pattern guards
- Invalid syntax, detected nested quantifiers, and patterns that match empty strings are rejected with an inline error.
Example
Pattern and text
(?<label>[A-Za-z]+) · alpha 42 beta
g flag
2 matches · label: alpha · label: beta
Good to know
- Patterns use JavaScript regular-expression syntax, which can differ from another language or service.
- Use the g flag when you want every match rather than only the first one.
- The pattern guards reduce specific risks but do not provide a general execution-time guarantee.