Regex Tester & Debugger

Enter your regex pattern in the pattern field and paste your test string below it. Matches are highlighted instantly as you type, showing you exactly what your pattern captures. This is ideal for building and debugging regex for JavaScript, Python, or any language that uses standard regex syntax.

Toggle flags using the badges below the pattern input. The global flag (g) finds all matches, case-insensitive (i) ignores letter casing, and multiline (m) makes ^ and $ match line boundaries instead of string boundaries. You can combine multiple flags for precise control.

Wrap part of your pattern in parentheses to create a capture group that extracts matched substrings. Named groups use the syntax (?<name>...) for clarity. This tool displays each group separately so you can verify your extraction logic before adding it to your code.

Yes. All pattern matching runs entirely in your browser using the native JavaScript regex engine. Your patterns and test strings are never transmitted to any server, making it safe for testing against sensitive data like log files or user input.

Enable Replace mode, enter your replacement string, and see the output update in real time. You can use backreferences like $1 for numbered groups or $<name> for named groups. This is useful for reformatting dates, restructuring CSV data, or batch-renaming patterns.