Regex Tester

When to use Regex Tester

You're writing a log-parsing script to extract error codes from Nginx access logs and you've iterated on the same pattern four times without running the script each time — or you need to verify that your email validation regex doesn't also match `user@@example..com` before it ships to production. Paste the pattern, set your flags, and native JavaScript RegExp highlights matches in real time with capture groups broken out by index so you can see exactly what's captured and what isn't. Test against real production log samples or real email addresses — no data leaves the browser, so PII and internal identifiers stay in the tab. When the pattern looks right, copy it straight into your code.

• Validate an email regex against real addresses before it ships
• Iterate on a log-parsing pattern without re-running the script each time
• Debug a route matcher that is catching too many URL paths

About this tool

Regex is hard. Test yours here before you commit it. Paste your pattern, enter test strings, and see matches highlighted in real time with capture groups broken out by index. Supports all standard JavaScript flags: global, case-insensitive, multiline, and dotAll. Useful for validating an email regex before it ships, debugging a route pattern that matches too broadly, or iterating on a log-parsing expression without rerunning a script each time. No data leaves your browser — test strings with real PII, internal identifiers, or production log samples without sending them anywhere. Get the pattern right, then copy it.