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Regex Tools

Test, debug, and learn regular expressions with interactive tools.

1 free tools available

Regular expressions are one of the most powerful tools in a developer's toolkit, but they can also be challenging to write and debug. Our free regex tools help you build, test, and refine regular expression patterns with instant visual feedback. See matches highlighted in real time, inspect captured groups, and iterate on your patterns until they work exactly as intended.

Whether you are validating user input, extracting data from log files, performing search-and-replace operations in code, or parsing structured text, our regex tools make the process faster and less error-prone. They are used by frontend and backend developers, data analysts, DevOps engineers, and anyone who works with text pattern matching. Test your patterns against sample data right in your browser with no setup required, and gain confidence before deploying them in your application.

Regex Tester & Debugger
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Test and debug regular expressions

Frequently Asked Questions

What is a regular expression (regex)?▾
A regular expression is a sequence of characters that defines a search pattern. It is used for pattern matching within strings, enabling operations like searching, validating, extracting, and replacing text. Regular expressions are supported by virtually every programming language and many command-line tools, making them an essential skill for developers.
Which regex flavors are supported?▾
Our regex tools use JavaScript's built-in regular expression engine, which follows the ECMAScript specification. This is compatible with regex patterns used in JavaScript, TypeScript, and most web-based environments. While there are minor differences from PCRE (used in PHP and many other languages) or Python's regex engine, the vast majority of common patterns work identically across all flavors.
Can I test regex patterns with multiple flags?▾
Yes. Our regex tester supports all standard JavaScript regex flags including global (g), case-insensitive (i), multiline (m), dotAll (s), and unicode (u). You can combine multiple flags to fine-tune your pattern matching behavior. The tool highlights matches in real time and shows captured groups for each match.
How can I learn regular expressions as a beginner?▾
Start with simple patterns like literal string matching, then gradually learn character classes ([a-z], \d, \w), quantifiers (*, +, ?), anchors (^, $), and grouping with parentheses. Our regex tester is a great learning tool because it provides instant visual feedback as you modify your pattern. Practice with real-world examples like email validation, phone number matching, and URL extraction.
Why is my regex matching more or less than expected?▾
Common issues include greedy vs. lazy quantifiers (using .* vs. .*?), forgetting anchors (^ and $) for full-string matching, not escaping special characters (like dots and parentheses), and missing the global flag when you want all matches. Our tools highlight every match in your test string, making it easy to identify and fix these issues by seeing exactly what your pattern captures.