Free · no signup · browser-local
Regular Expression Tester
Inspect matches and capture groups with a bounded worker execution.
Private by design: files and input stay in this browser. No account or upload.
Runs in an isolated Worker, stopped after 500 ms; up to 200 matches / 1M output characters. Empty matches advance safely. Without g or y, only the first match is returned. Supported flags depend on your browser.
Getting started
Enter a pattern, flags and sample text, then run the test.
Before you use the result
Complex expressions time out rather than blocking the page.
Frequently asked questions
Inspect matches and capture groups with a bounded worker execution.
How do I use Regular Expression Tester?
Enter a pattern, flags and sample text, then run the test.
Does this tool upload my data?
Inputs and files are processed in your browser. Page-view analytics do not contain your tool input.
What should I check before using the result?
Complex expressions time out rather than blocking the page.