Regex Tester

Free Online Regex Tester – Test Regular Expressions Instantly

Test and debug regular expressions with live match highlighting, capture groups, and easy flag toggling — all in your browser.

Hey there! Regular expressions (regex) are incredibly powerful but can be tricky to get right. Our free Regex Tester helps you write, test, and debug patterns in real time. As you type your regex and test string, matches highlight instantly, and you can see all capture groups clearly.

Everything runs in your browser — 100% private and no data is sent anywhere.

What Is a Regular Expression?

A regex is a sequence of characters that defines a search pattern. It’s used for validating emails, extracting phone numbers, parsing logs, replacing text, and much more.

How to Use the Regex Tester

1. Type your regular expression in the pattern field (e.g. \b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b for emails).
2. Enter or paste a test string in the large text area.
3. Toggle flags (g, i, m, s, u) as needed.
4. Watch matches highlight live and see detailed results below.

Key Features

• Real-time matching with highlighted results
• Support for all common regex flags (global, case-insensitive, multiline, dotall, unicode)
• Shows all capture groups with their values and positions
• Clear error messages when your pattern is invalid
• Sample buttons with common regex patterns (email, phone, URL, etc.)
• One-click copy of all matches
• 100% browser-based and completely private

Common Regex Use Cases

• Validating email addresses
• Extracting phone numbers or ZIP codes
• Searching for URLs or specific patterns in logs
• Replacing text with find-and-replace operations
• Parsing structured data from large text files

Pro Tips

• Use the g flag to find all matches instead of just the first one
• Enable i for case-insensitive matching
• Use the sample buttons to quickly test common patterns
• Always test your regex with real-world data before using it in code

Why Developers Love This Regex Tester

• Forever free with no limits or ads
• Instant live feedback as you type
• Clear visualization of matches and groups
• Works smoothly on desktop and mobile
• 100% private — your patterns and test data never leave your browser

Ready to Test Your Regex?

Stop guessing whether your regular expression works. Test, debug, and perfect it instantly.

→ Open the Regex Tester Now – Free & Instant