Online Regex Tester
Test regular expressions online with live match highlighting. JavaScript regex flavor with flags support.
Frequently asked questions
- Which regex flavor does this tool use?
- It uses JavaScript (ECMAScript) regular expressions, so patterns and behavior match what you would get in browsers and Node.js.
- How do the flags work?
- Type any combination of flags such as g for global, i for case-insensitive, m for multiline, s for dotall or u for Unicode into the Flags field, and the test reruns immediately.
- Why does the output show fewer matches than the count?
- The count shows the total number of matches, while the list below shows up to 40 unique matches, so duplicates are collapsed to keep the output readable.
- What happens if my pattern is invalid?
- The error message from the JavaScript regex engine is displayed in red, which usually tells you exactly which part of the pattern failed to compile.
This tool runs entirely in your browser. No data is uploaded anywhere.