Regular Expression Tester
Test JavaScript patterns in a worker with a bounded execution time.
How to use this tool
- Enter values or select a file in the labelled controls.
- Select the action button and review the result.
- Copy the result or use its download control when available.
Runs in an isolated Web Worker with a 750 ms limit and a 5,000-match cap. A timeout means the pattern needs simplifying; it is not proof that the expression is invalid.
Processing takes place in this browser. Your entries are not sent to a conversion service.