1
Enter a pattern
Write the expression without slash delimiters and choose flags.
Developer Tools
Free tool
Regex Tester
Run a regular expression against sample text in your browser and inspect every match locally.
No account needed · Processed in your browser
How to test a regular expression
The JavaScript engine checks your text in an isolated worker.
2
Add test text
Paste a sample into the editor; Ctrl/Cmd + Enter runs the test.
3
Inspect matches
Check indexes, text and capture groups, or fix the reported error.
Understand the matches
Test JavaScript regular expressions against sample text locally. Matches and capture groups stay in your browser.
Pattern, flags and text
The JavaScript engine applies the pattern and flags to your sample. The g flag finds all matches; without it, the first match is returned.
Example: proper names
\b[A-Z][a-z]+\b with g finds Ada and Grace in “Ada met Grace”.
The engine limits execution time and match count.
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View allFrequently asked questions
What does zero matches mean?
The pattern is valid, but it does not match the selected text and flags.
Is my text uploaded?
No. Testing runs locally in your browser.