Free Tool

Regex Tester

Test regular expressions in real time. See matches highlighted, view capture groups, and toggle flags. Uses JavaScript regex syntax.

Regular Expression

//g

Flags:

Test String

How to Use

How to use the Regex Tester

Enter your regex pattern

Type your regular expression in the pattern field. The tool highlights syntax in real time and flags errors immediately.

Set flags

Toggle flags like global (g), case-insensitive (i), and multiline (m) depending on your matching needs.

Add test strings

Paste or type the text you want to match against. Matches are highlighted in real time as you type.

Review matches and groups

See all matches, captured groups, and their positions listed below. Use this to debug and refine your pattern.

Features

Why use our Regex Tester?

Real-Time Matching

Matches highlight instantly as you type — both in the pattern and test string. No execute button needed.

Match Highlighting

Color-coded highlights show each match and captured group directly in the test string for easy visual debugging.

Capture Group Display

Named and numbered capture groups are listed with their values and positions for every match.

Flag Toggles

One-click toggles for global, case-insensitive, multiline, dotAll, and unicode flags.

Error Detection

Invalid patterns are flagged instantly with clear error messages explaining what went wrong.

100% Client-Side

Runs JavaScript's native RegExp engine in your browser. Nothing is sent to a server.

FAQ

Regex Tester — Common Questions

Regex (regular expressions) is a pattern-matching language used in programming to search, match, and manipulate text. For example, the pattern \d{3}-\d{4} matches phone number formats like 555-1234.

Yes, 100% free with no sign-up. Test as many patterns as you like with no limits.

It uses JavaScript's built-in RegExp engine, which supports the ECMAScript regex standard. This covers named groups, lookbehind, Unicode properties, and all modern features available in browsers.

The tool runs JavaScript regex, which covers most common patterns. Python and PHP have minor syntax differences (like possessive quantifiers), but 95% of patterns work the same across languages.

g (global) finds all matches, i (case-insensitive) ignores case, m (multiline) makes ^ and $ match line boundaries, s (dotAll) makes . match newlines, and u (unicode) enables full Unicode support.

Yes. All matching runs in your browser using JavaScript. No patterns or test strings are sent to any server.

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