Regex Tester
A powerful, real-time regular expression editor and debugger. Input your pattern and test string to see instant matches and captures.
Results will appear here
Pattern Explanation
Enter a valid regular expression above to see a breakdown of its logic.
Revolutionizing Pattern Recognition
RegexTool is not just a utility; it's a sophisticated ecosystem designed to bridge the gap between complex computer science theory and practical, everyday development. Regular expressions are the unsung heroes of software engineering, powering everything from compiler lexers to high-frequency trading logs.
Our platform leverages the latest advancements in client-side execution. By utilizing the native JavaScript RegExp engine, we ensure that what you see in our debugger is exactly what you get in your production environment. Whether you are validating a simple email field or parsing multi-gigabyte server logs, RegexTool provides the precision and speed you need.
Core Capabilities
Non-Capturing Groups
Optimize your patterns by using (?:...) to group without the
overhead of memory allocation for capture.
Lookarounds
Implement powerful logic like "match X only if followed by Y"
using (?=...) and (?!...).
Why RegexTool?
- Zero Latency: Since all computations happen on your local machine, there's no network delay between typing and seeing results.
- Privacy by Design: Your sensitive data never leaves your browser. We don't log your patterns or your test strings.
- Advanced Debugging: Our unique match highlighting system breaks down complex captures, making it easy to see exactly what your regex is doing.
Regex Cheat Sheet
^ / $
Start and end of string anchors.
\d / \D
Digit vs. Non-digit characters.
\w / \W
Word characters (A-Z, 0-9, _) vs. non-word.
\s / \S
Whitespace vs. non-whitespace.
? / * / +
Quantifiers: 0 or 1, 0 or more, 1 or more.
{n,m}
Match between n and m times.
Pro Tip
Use the 'i' flag for case-insensitive matching, and the 'g' flag to find all matches rather than just the first one.