Regex Tester & Debugger
Test regular expressions live with match highlighting, group capture display, and detailed regex execution explanation.
Regex Tester
What is Regex Tester & Debugger?
Regex Tester & Debugger is an interactive online tool for testing debugging and learning JavaScript-compatible regular expressions in real time. Regular expressions regex or regexp are powerful pattern-matching notations used across virtually every programming language for string validation text extraction find-and-replace operations input sanitization and log analysis. This Regex Tester features a pattern input with flag toggles g global i case-insensitive m multiline s dotAll u unicode a test string area and color-coded match highlighting that shows each match and its capture groups distinctly. The debugger panel displays every match with its index position full matched text and all captured subgroups plus a match replacement mode that lets you test substitution patterns with dollar one dollar two backreferences. Built-in regex reference cards and a cheat sheet make this tool equally valuable for seasoned developers and those learning regular expressions for the first time.
When to Use Regex Tester & Debugger
Use when validating form inputs, writing extraction patterns, debugging regex in production code, learning regex syntax, or testing replace operations before deployment.
How to Use Regex Tester & Debugger
Enter your regex pattern and flags in the top field. Type or paste test text below. Matches highlight in real time. Switch to replace mode to test substitution patterns with capture group references.
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