Regex Tester
Test and debug JavaScript regular expressions in real-time. Includes highlighting, match details, and a quick reference cheatsheet.
Cheatsheet
Match Info
About Regex Tester
Regular expressions (Regex) are powerful tools for pattern matching and text manipulation. This online Regex Tester allows you to write and test your regular expressions against any text string in real-time.
Whether you are a developer debugging a complex pattern or a beginner learning the syntax, this tool provides instant feedback with visual highlighting and detailed match information.
Features
- Real-time Testing: See results instantly as you type.
- Syntax Highlighting: Matches are clearly highlighted in the text.
- Flag Support: Toggle global, case-insensitive, multiline, and other flags.
- Detailed Breakdown: View capture groups and match indices.
Frequently Asked Questions
What is a Regular Expression?
A regular expression (shortened as regex or regexp) is a sequence of characters that specifies a search pattern in text. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation.
Which Regex engine does this tool use?
This tool runs entirely in your browser and uses JavaScript's built-in RegExp engine. Results match exactly how your regex behaves in any JavaScript environment (Node.js, Chrome, Firefox, etc.).
How do I use flags?
Click the button next to the regex input field to open the flags menu. You can toggle flags like 'g' (Global search), 'i' (Case-insensitive search), and 'm' (Multiline search).
Why isn't my regex matching?
Common reasons include: forgetting the global flag 'g' when you want multiple matches, case sensitivity issues (try 'i' flag), or special characters not being escaped properly (like `.` or `?`). Use the cheatsheet to verify your syntax.
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