How do I test a regular expression online for free?

Enter your regex pattern in the Pattern field, paste your test string in the Test String area, select flags (g for global, i for case-insensitive), and click Test Regex. Matches are highlighted instantly. No signup, 100% free.

What regex flags does this tool support?

The regex tester supports g (global - find all matches), i (case insensitive), m (multiline - ^ and $ match line boundaries), and s (dotAll - dot matches newlines).

Does this regex tester use JavaScript regex syntax?

Yes. This tool uses JavaScript's built-in RegExp engine. The syntax follows JavaScript regular expression rules, making it ideal for testing patterns used in web development.

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🔍 Regex Tester Online Free

Test regular expressions online — paste your pattern, see matches highlighted instantly. Supports g, i, m, s flags. No signup, 100% browser-based.

🔍 Regex Pattern

g Global i Case insensitive m Multiline s DotAll

📝 Test String

Matches Highlighted

📚 Regex Quick Reference

Any digit 0-9

Word char a-z A-Z 0-9 _

Whitespace space tab

Any character except newline

Start of string/line

End of string/line

One or more

Zero or more

Zero or one (optional)

{n,m}

Between n and m times

[abc]

Character class a, b, or c

(abc)

Capture group

Regex Tester Online Free — Test Regular Expressions Instantly

Our free online regex tester lets you test regular expression patterns and see matches highlighted in real time. Supports JavaScript regex syntax with g, i, m, and s flags. Works in your browser — no server, no account needed.

What is a Regular Expression?

A regular expression (regex) is a sequence of characters that defines a search pattern. Used in programming, text editing, and data validation to find, match, extract, or replace text. Regex is supported in Python, JavaScript, Java, PHP, and virtually every programming language.

Common Regex Patterns

Email: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}
Phone (US): $?\d{3}$?[-.\s]?\d{3}[-.\s]?\d{4}
URL: https?://[^\s]+
IP Address: \d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}
Only digits: ^\d+$
Date YYYY-MM-DD: \d{4}-\d{2}-\d{2}

Regex Flags Explained

g (global) — Find all matches, not just the first one
i (case insensitive) — Match regardless of uppercase or lowercase
m (multiline) — ^ and $ match start/end of each line
s (dotAll) — Dot . matches newline characters too

JavaScript Regex Syntax

This tool uses JavaScript's RegExp engine — the same regex used in web browsers and Node.js. Patterns work directly in JavaScript code: const regex = /pattern/flags;

How to Use the Regex Tester

Enter your regular expression pattern
Paste the test text you want to check against it
Click Test Regex to see matches highlighted instantly
Use the Quick Reference cheat sheet for common regex symbols

Frequently Asked Questions — Regex Tester

How do I test a regex pattern online for free?

Enter pattern, paste test string, select flags, click Test Regex. Matches highlighted instantly. No signup, free.

What flags does this regex tester support?

Supports g (global), i (case insensitive), m (multiline), and s (dotAll) flags.

What is a regular expression?

A regex is a pattern for searching and matching text. Used in all programming languages for finding, validating, and manipulating strings.

Does this use JavaScript regex syntax?

Yes — uses JavaScript built-in RegExp engine. Same syntax as used in browser and Node.js development.

How do I match email addresses with regex?

Use pattern: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,} with g flag to find all emails in text.