Regex Tester & Debugger

What is the Regex Tester?

The Regex Tester is a free online developer utility that allows you to write, test, and debug Regular Expressions (Regex) in real-time. Regular expressions are powerful sequences of characters that define a search pattern, commonly used for string matching, data validation (like emails or phone numbers), and text extraction. However, writing them can be notoriously difficult. This tool provides instant visual feedback, making it easy to see exactly what your pattern is matching.

How to Use the Regex Tester

Using the tool is intuitive and fast:

1. Enter your Pattern: Type your regular expression in the top input box (without the surrounding forward slashes /).
2. Select Flags: Toggle the flags on the right side. Use g for global search (find all matches), i for case-insensitive search, and m for multiline matching.
3. Enter Test String: Paste the text you want to search against in the large text area.
4. View Results: The tool will instantly highlight all matches directly within your text. Scroll down to the "Match Results" section to see the exact index and capture groups for every match.

100% Secure and Client-Side

When testing regular expressions against sensitive data like server logs, customer emails, or proprietary code, privacy is essential. ToolDojo's Regex Tester processes everything locally in your web browser. Your patterns and test strings are never transmitted over the internet or saved to any server, ensuring complete security for your development workflow.