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Regex Tester – Test Regular Expressions Online

Test regular expressions with flags and see matches instantly.

No uploads. Everything runs locally in your browser.

Regex tester

Test regular expressions with flags, see matches and positions instantly, and tweak patterns without sending data to a server.

Use examples to jump-start common patterns like emails, URLs, dates, and numbers.

Pattern
Flags
Text
Matches
  • foo at index 0
  • bar at index 8

What is this tool

This regex tester lets you try regular expressions with flags, preview matches and positions, and iterate quickly—all in your browser.

Use cases

  • Validate form inputs like emails, URLs, and numbers.
  • Debug search-and-replace patterns before using them in code.
  • Test extraction rules for logs, CSVs, or text files.
  • Prototype regex for scripts, API filters, or data pipelines.

Popular ways to use this tool

How to use Regex Tester

  1. Enter a regex pattern and optional flags (g, i, m, s, u, y).
  2. Paste sample text to test against the pattern.
  3. Review matches with their positions and tweak the regex as needed.

Key features of Regex Tester

  • Client-side regex testing for privacy
  • Supports standard flags (g, i, m, s, u, y)
  • Shows matched text with positions
  • Quickly switch patterns with examples
  • Works on desktop and mobile browsers

Regex Tester — key benefits

  • Completely free with no signup or registration required.
  • Runs entirely in your browser — your data is never uploaded.
  • Works on desktop, tablet, and mobile devices.
  • Instant results with no waiting or processing queues.
  • Part of the ToolCircuit suite of free online developer tools tools.

FAQ

Is this regex tester free?

Yes. It runs in your browser at no cost.

Is my text sent to a server?

No. Matching happens locally in your browser.

Can I test with flags?

Yes. Use flags like g, i, m, s, u, y as needed.

Does it work on mobile?

Yes. You can test regex patterns on phones and tablets.

Can I see match positions?

Yes. Each match shows its index in the text.

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