Regex generator & tester

Client

Pick a common pattern (phone presets use US/NANP and E.164—not country-specific China mobile rules), edit flags, generate new RegExp(...) code, or run a quick test—all client-side.

Common patterns

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One tap fills the pattern (and flags when needed). Phone presets use US/NANP and E.164—suitable for North American and international +country formats, not country-specific rules outside those scopes.

JavaScript

Common use cases

  • Draft validation patterns for emails, URLs, and phone-like inputs before shipping UI forms.
  • Test extraction patterns on sample logs or text without writing a script first.
  • Generate JavaScript RegExp snippets with flags for quick copy into app code.

Common mistakes to avoid

  • Forgetting to escape special characters

    Characters like . + * ? ( ) [ ] and { } are operators in regex unless escaped with a backslash.

  • Using greedy patterns where bounded matches are safer

    A broad pattern such as .* can over-capture. Prefer stricter character classes and anchors when possible.

  • Assuming one pattern works in every engine

    Regex dialects differ across JavaScript, PCRE, and other runtimes. Verify syntax in your target runtime before release.

FAQ

Can I use this page for both generation and testing?

Yes. The workspace supports preset-driven generation and a separate test mode so you can verify matches against sample strings.

Why does a regex work here but fail in another tool?

Different runtimes support different tokens and flags. Treat this page as a fast drafting tool, then confirm behavior in your production engine.

Does regex input leave my browser?

No. Pattern editing and testing run locally in your browser tab.

More tools

Related utilities you can open in another tab—mostly client-side.