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Quick Reference
Characters
.any character except newline\ddigit (0-9)\wword character (a-z, A-Z, 0-9, _)\swhitespace\D \W \Snot digit/word/whitespaceQuantifiers
*0 or more+1 or more?0 or 1{n}exactly n{n,m}between n and mAnchors
^start of string/line$end of string/line\bword boundary\Bnot word boundaryGroups & Flags
(abc)capture group(?:abc)non-capturing group[abc]character classa|balternation (or)g i m sflagsKey Features
Everything you need, right at your fingertips. Simple, fast, and built for everyone.
Live Matching
See matches highlight in real-time as you type your pattern.
All Flags Supported
g, i, m, s, u, y —every JavaScript RegExp flag available.
Capture Groups
See all matched groups clearly listed with their values.
Match Counter
Know exactly how many matches were found.
Test String Library
Experiment with sample text or paste your own.
Cheat Sheet
Quick reference for common regex patterns and syntax.
How to Use This Regex Tester
Getting started is easy. Just follow these simple steps.
Write Your Pattern
Enter your regex in the pattern field.
Choose Flags
Toggle global, case-insensitive, multiline, etc.
Paste Test Text
Drop the string you want to test against.
View Matches
See highlighted matches, group details, and match count.
About This Regex Tester
Regular expressions (regex or regexp) are powerful patterns for matching, searching, and manipulating text. They are used in programming, text editors, command-line tools, and many software applications for everything from form validation to complex text processing.
Learning regex can feel like learning a new language at first, but once you understand the basics, it becomes an indispensable tool. Common regex patterns include character classes ([a-z]), quantifiers (*, +, ?, {n,m}), anchors (^, $), groups and capture, alternation (|), and lookaheads and lookbehinds.
Regex is supported by virtually every programming language and most modern text editors. It is one of the most transferable skills a developer or data professional can learn. From validating email addresses to parsing log files to performing complex find-and-replace operations, regex can save you hours of manual work.
A regex tester is the best way to build, test, and debug your regular expressions. By testing your pattern against sample data in real time, you can see exactly what matches and what does not, understand how groups are captured, and iterate quickly until your pattern works perfectly.
Frequently Asked Questions
What are developer tools?
Developer tools are software utilities that help programmers build, test, debug, and optimize code and applications. They include code editors, debuggers, version control, testing frameworks, and online utility tools.
What is a regex tester used for?
A regex tester lets you write and test regular expressions against sample text in real time. It helps you build, debug, and understand regex patterns before using them in your code.
What is a regular expression?
A regular expression (regex) is a sequence of characters that defines a search pattern. It is used to find, replace, or validate text patterns in strings. Regex is supported by most programming languages and text editors and is essential for text processing tasks.
How do I test a regex pattern?
Use an online regex tester like RegexTester to paste your pattern and test it against sample text. You can see matches in real-time, check which groups are captured, and experiment with different flags. Always test edge cases like empty strings, special characters, and very long inputs.