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Regex Tester Online

Test regular expressions instantly with flags, inspect all matches, highlight matching text, and debug patterns in your browser. This regex tester is useful for developers, testers, analysts, students, and anyone working with text matching rules.

Last updated: March 2026
Regex Pattern
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Fast • Free • Live Matching

Test regex patterns instantly with flags and highlighted matches

Regular expressions are powerful but difficult to debug without instant feedback. This page lets you test patterns live, inspect matches, highlight matching text, and work with flags like global, case-insensitive, multiline, dotall, and unicode.

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Your text stays in the browser

This regex tester is designed to work directly in your browser during normal use. That makes it useful for quick testing, debugging, validation, and pattern experimentation without extra setup.

For more details about analytics and site usage, review our Privacy Policy.

How to use this Regex Tester

Enter a regex pattern, choose the flags you want, paste your sample text, and run the test. The tool shows matched text in a preview panel and lists detailed match information in the results area.

  1. Enter your regex pattern.
  2. Select the flags you want to use.
  3. Paste or type the test text.
  4. Click Test Regex.
  5. Review highlighted matches and detailed results.

Example pattern

[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-z]{2,}

Common use cases

  • Email validation patterns
  • Log parsing
  • Text extraction
  • Form input testing
  • String matching and cleanup

What is a regex tester?

A regex tester is a tool that helps you test regular expressions against sample text. It shows whether your pattern matches, how many matches are found, and which parts of the text are captured or highlighted.

This is useful for validating emails, searching logs, parsing structured strings, filtering text, extracting values, and debugging complex regular expression patterns.

What is regex used for?

Regex is used to search, validate, match, replace, and extract text patterns from strings. It appears in development, data cleaning, automation, QA, log inspection, and many kinds of text processing workflows.

  • Validation: check formats like email, phone, and IDs.
  • Extraction: pull values from larger blocks of text.
  • Search: find repeated or structured patterns quickly.
  • Replacement: clean or transform text with pattern rules.

What do regex flags mean?

Regex flags change how the pattern behaves. For example, g finds all matches, i ignores case, m enables multiline matching, s changes dot behavior to include line breaks, and u enables unicode-aware matching.

Frequently Asked Questions

What is regex used for?

Regex is used to search, validate, match, replace, and extract text patterns from strings. Common uses include email validation, log parsing, form validation, and text processing.

What do regex flags mean?

Flags modify regex behavior. For example, g finds all matches, i ignores letter case, and m enables multiline matching.

Can I test multiple matches at once?

Yes. With the global flag enabled, this tool finds and lists all matches in the provided text.

Does this tool highlight matched text?

Yes. The preview panel highlights matching text so you can easily see what your regex captures.

Is this regex tester free?

Yes. ToolzYard provides this regex tester for free directly in your browser.

Does this tool upload my text?

No. This tool works entirely in your browser, so your text and regex pattern stay on your device.