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Regex Tester

Test JavaScript regex patterns against sample text with live highlighting.

Test JavaScript regex patterns against sample text with live highlighting.

Quick start: Enter your regular expression pattern in the pattern field at the top. → Set regex flags (global, case-insensitive, multiline) using the flag toggles. → Paste or type sample text in the test area below.

How to use Regex Tester

  1. 1

    Enter your regular expression pattern in the pattern field at the top.

  2. 2

    Set regex flags (global, case-insensitive, multiline) using the flag toggles.

  3. 3

    Paste or type sample text in the test area below.

  4. 4

    Watch matches highlight in real time as you type — both pattern and test text trigger updates.

  5. 5

    Review the match count, captured groups, and match positions displayed below the test area.

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Why use Regex Tester?

  • Live match highlighting updates as you type, giving instant visual feedback.
  • Displays captured groups, match indices, and total match count for thorough debugging.
  • Supports all JavaScript regex flags including global, case-insensitive, multiline, and dotAll.
  • Runs entirely in your browser — your test data is never sent to a server.

Common use cases

  • Debug and refine log-parsing regex patterns before deploying them in production code.
  • Test email, URL, or phone number validation patterns against edge-case inputs.
  • Build search-and-replace patterns for text processing scripts.
  • Learn regular expressions by experimenting with patterns and seeing matches highlighted in real time.

About Regex Tester

Regular expressions are one of the most powerful yet error-prone tools in a developer's arsenal. Xevon Tools' Regex Tester provides a real-time testing environment where matches highlight instantly as you type both the pattern and the test text. The tool displays the total match count, individual match positions, and captured group values — everything you need to verify a pattern works correctly before using it in production code. Flags like global, case-insensitive, multiline, and dotAll are configurable via toggles. The testing engine uses JavaScript's native RegExp, so patterns are directly compatible with front-end code, Node.js, and any JavaScript runtime. Whether you are building validation patterns for forms, parsing structured log files, or learning regex for the first time, this tool provides the immediate feedback loop that makes pattern development efficient and reliable. Everything runs in your browser with no server involvement.

Frequently asked questions

The tool uses JavaScript's native RegExp engine, which is the same one running in all major browsers and Node.js. Patterns are fully compatible with JavaScript code.
Yes. When your pattern contains capturing groups (parentheses), each match displays the captured group values alongside the full match, making it easy to extract specific parts of a pattern.
Yes. Modern browsers support both lookahead (?=...) and lookbehind (?<=...) assertions. The tool reflects whatever your browser's JavaScript engine supports.
Currently patterns are not saved between sessions. Copy your pattern and test text before leaving the page. Sharing and pattern history features are planned for a future update.

Your files never leave your device

Every tool on Xevon Tools runs 100% in your browser. No uploads, no servers, no tracking. Free forever.

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Embed Regex Tester on your site

Add this tool to your own website, blog, or internal tool page with one line of code. Free to use, no attribution required (but appreciated).

<iframe src="https://www.xevontools.com/embed/regex-tester" width="100%" height="640" style="border:1px solid #e2e8f0;border-radius:12px;" title="Regex Tester — Xevon Tools"></iframe>
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