Regex Tester Online — Evaluate Regular Expressions

What is a Regex Tester?

A Regular Expression (Regex) Tester is a utility designed to help developers write, test, and debug complex string matching patterns. Writing regex can be notoriously difficult, and seeing visual, instant feedback is the best way to ensure your pattern matches exactly what you intend.

Our Regex Tester evaluates your pattern directly in your browser, highlighting the exact character ranges that match.

Features

• Real-Time Evaluation: As you type your pattern, the test string is instantly evaluated and highlighted.
• Match Counting: Automatically tracks and displays the total number of distinct matches.
• Color Cycling: Consecutive matches are highlighted in alternating colors to clearly define boundaries.
• 100% Private: Your sensitive test strings and patterns never leave your device.

How to use

1. Enter Pattern: Type your regular expression in the / / input box.
2. Set Flags: Add flags like g (global), i (case-insensitive), or m (multiline) in the flags box.
3. Test String: Provide the text you want to match against in the bottom left text area.
4. View Results: See the highlighted output in the right panel.