Regular Expression Tester
Test JavaScript regex patterns up to 200 UTF-16 units on 20000-unit text. Global search, optional ignore case, match positions and Worker timeout.
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Regular Expression Tester
Test JavaScript regular expressions with global and optional case-insensitive matching. See matches and their zero-based UTF-16 positions.
Worked example
\b\d+\b Order 123, amount 456
1. 123 (6) 2. 456 (18)
Input and calculation
Enter the JavaScript pattern \b\d+\b without surrounding slashes. Paste Order 123, amount 456 as the test text.
Run the test. Expect 123 at zero-based UTF-16 position 6 and 456 at position 18. Matching is global; Ignore case adds the i flag.
Limits
The pattern accepts 1–200 UTF-16 code units and test text up to 20000. Capture groups may affect matching but their contents are not displayed; replacement and additional flags are not exposed. Verify behavior in your target JavaScript runtime.
Matching runs in a browser Worker. Startup is limited to 10 seconds; once ready, execution has an approximately 1.5-second deadline, then the Worker is terminated. This is not a promise that the entire page action finishes in 1.5 seconds. At most 10000 matches are returned; exceeding the cap rejects the result rather than showing a partial list. Simplify slow patterns or reduce the text.
Processing takes place locally in your browser.