Regex Tester Online Free

Need to test regex in JavaScript without setting up a dev environment?

This free regex tester runs JavaScript RegExp directly in your browser. Enter your pattern, paste your test string, and see matches highlighted instantly.

Since this tool uses the same regex engine as your JavaScript code, patterns you build here work exactly the same in Node.js, React, or any JS environment. No surprises when you copy them into your project.

Whether you are validating form input, parsing API responses, or debugging a tricky pattern, this regex testing tool online helps you get it right before committing code.

• ✔ Real JavaScript RegExp: Same engine as your code
• ✔ Live regex test and match: Results update as you type
• ✔ View capture groups with index positions
• ✔ All JS flags supported: g, i, m, s, u
• ✔ Copy regex in /pattern/flags format
• ✔ Common patterns library for quick starts
• ✔ 100% browser-based: Nothing sent to servers
• ✔ Regex tester online free: No account needed

If you have used regex101 or regexr, this is a lightweight JavaScript-focused alternative. No flavor confusion since it only runs JS regex.

1. Enter Your Regex Pattern

Type your JavaScript regular expression in the pattern field. Use the common patterns dropdown for email, URL, phone, and other frequently used patterns.

2. Paste Your Test String

Add the text you want to match against. The tool handles multi-line strings, so paste log files, JSON, or any text you need to parse.

3. Select Flags

Choose JavaScript regex flags: global (g), case-insensitive (i), multiline (m), dotAll (s), or unicode (u). Combine them as needed.

4. View Matches and Groups

See matches highlighted in your test string. The details panel shows each match with capture groups and their index positions.

This regex test JS tool supports all standard JavaScript flags:

• g (Global): Find all matches, not just the first
• i (Case Insensitive): Ignore uppercase/lowercase differences
• m (Multiline): ^ and $ match line starts/ends, not just string
• s (DotAll): Dot (.) matches newlines too
• u (Unicode): Enable full Unicode matching

Example: /pattern/gi finds all matches regardless of case.

This is a JavaScript regex tester. It uses the browser's native RegExp engine, which means:

• Patterns work identically to JS code (Node.js, browsers, Deno)
• ES2018+ features like lookbehind assertions are supported
• Named capture groups work as expected

Not supported: This tool does not support PCRE, Python re, Java regex, or .NET flavors. Those engines have different syntax for features like possessive quantifiers or conditionals. If you need those, use a flavor-specific tester.

Quick reference for frequently used JS patterns:

• Email: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}
• URL: https?:\\/\\/[\\w\\-._~:/?#[\\]@!$'()*+,;=]+
• Phone (US): \\(?\\d{3}\\)?[-.\\s]?\\d{3}[-.\\s]?\\d{4}
• IP Address: \\b(?:\\d{1,3}\\.){3}\\d{1,3}\\b
• ISO Date: \\d{4}-\\d{2}-\\d{2}
• Hex Color: #(?:[0-9a-fA-F]{3}){1,2}\\b
• UUID: [0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}

Click "Common Patterns" in the tool to insert these automatically.

JavaScript has two main methods: regex.test(string) returns true/false, while string.match(regex) returns the actual matches.

This tool shows you both: whether your pattern matches (test) and what it captures (match). Use test() when you only need validation. Use match() when you need to extract data.

• test(): Validation, conditionals, quick checks
• match(): Extracting values, capture groups, replacements
• matchAll(): Multiple matches with all capture groups (ES2020)

Looking for ready-to-use regex patterns for your JavaScript project? Check out our complete guide: JavaScript Regex Examples: 10 Patterns You Can Copy. It includes tested patterns for email validation, phone numbers, URLs, dates, passwords, and more — all ready to paste into your code.

Unlike most "free" regex testers, we:

• Do not upload your files
• Do not store or track anything
• Do not require accounts

Everything happens locally in your browser. That means you can safely process sensitive documents like:

• API keys and secrets you are testing patterns for
• Log files with sensitive user data
• Internal code snippets
• Private configuration formats
• Proprietary data patterns

Your files stay on your device at all times.