Free Online Regex Tester & Debugger
Write and test regular expressions with instant visual feedback. See matches highlighted in real-time as you type, inspect capture groups and their values, toggle flags (global, case-insensitive, multiline, dotAll), and view detailed match information including indices and named groups. Essential for building and debugging regex patterns for form validation, text parsing, log analysis, and data extraction.
Common questions
Which regex flavor does this tool use?
This tool uses JavaScript's native RegExp engine, which supports all modern features including named capture groups (?<name>), lookbehind assertions (?<=), Unicode property escapes (\p{}), and the dotAll (s) flag.
Why does my regex work here but not in my code?
Different languages have slightly different regex implementations. Python, Java, and .NET may handle features like lookbehinds, possessive quantifiers, or Unicode differently. This tool matches JavaScript's behavior exactly.