Regex tester

How to use this tool

Test JavaScript patterns and inspect matches.

Paste or enter your content. The result updates as you type. Choose an option only when you need to change the default.

This tester uses the JavaScript regular-expression engine, not PCRE, Python or Go. Patterns run in an isolated worker with an execution timeout.

Example input

hello@example.com
invalid address
team@example.com

Local processing

Your input stays in this browser. Drafts are kept in page memory while switching tools, and disappear on reload.

Text is limited to 1 million characters. Regex runs in a worker, capped at 200,000 characters, 1,000 matches and 1.5 seconds. Inputs above 100,000 characters use manual refresh.

The first page load and on-demand modules require network access. A complete offline cache is not included.