Regex Tester Documentation

Test regular expressions against sample text to validate search and parse logic quickly.

Both actions execute JavaScript regexes in a dedicated Web Worker using the same flags. A one-second deadline terminates an unresponsive worker. Test pattern returns a boolean; Find all matches adds global enumeration and records UTF-16 positions, numbered captures, and named groups up to the output limit. Edits cancel prior work and clear results.

• Validate a regex before using it in code.
• Review every match position in a longer text sample.
• Extract named capture groups to confirm parsing logic.

Input

Text, files, or values entered in the browser, depending on the tool.

Output

A result shown in the browser that can be reviewed or copied where supported.

• Evaluation uses a dedicated worker terminated after one second, including startup; very slow devices may need smaller inputs.
• Limits are 2,000 pattern characters, 500,000 text characters, and 1,000 displayed matches. Supported syntax follows the browser, not PCRE or a server language.

Inputs for this browser-side tool are processed locally and are not sent to SiteIndex. Normal page analytics may still be collected as described in the Privacy Policy. Read the Privacy Policy.