EsyTool

Regex Tester Online

Use this free online Regex Tester tool to live regular expression tester and validator. Write patterns and highlight matches instantly.

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How it works & FAQ
Browser-Based

Why this is secure?

All regex matching runs in your browser's JavaScript engine. Your patterns and test strings are never transmitted to any server.

Step-by-Step Guide

  1. 1Enter your regular expression pattern in the Regex field.
  2. 2Set any flags (g, i, m, s, u) using the flag toggles.
  3. 3Paste your test string — all matches are highlighted instantly.

Frequently Asked Questions (FAQ)

Which regex flavor is used?

This tester uses JavaScript's built-in RegExp engine (ECMAScript regex), which supports lookaheads, lookbehinds, and named capture groups.

Can I see capture groups?

Yes. Capture groups are listed below the match highlights, showing each group's matched value by index and name.

Why doesn't my regex from another language work?

Different languages have different regex flavors. Features like \p{} Unicode properties or possessive quantifiers may not be supported in JavaScript regex.

Zero Data Leaks

Regex matching runs in your browser's JavaScript engine. No pattern or text data is sent anywhere.