Regular Expression Tester and Replace Tool
Check JavaScript and ECMAScript matches, capture groups, and replacement results in real time.
Your regular expressions, text, and files are processed only in your browser and are never uploaded or stored. Some syntax and behavior differ from Java, Python, .NET, and PCRE.
Regular expression
Test text
Matched text
Replacement test
Quick expression guide
This is a simple explanation of common tokens and does not guarantee that the entire expression is correct.
Match list
| No. | Match | Position | Line:column | Capture groups |
|---|
Status:
Matches: 0
Elapsed: -
About this tool
Before adding a regular expression to your code, check its match positions, captured values, and replacement output against sample text.
Features
- JavaScript and ECMAScript regular expressions with the g, i, m, s, u, v, and y flags
- Highlighted matches, line and column positions, numbered and named captures, and replacement results
How to use
- Enter a regular expression or select a preset for a common use case.
- Enter test text or load a local text file from your device.
- Review the matched text, capture groups, and replacement result.
Limitations
- Some syntax and behavior differ from regular expressions in Java, Python, .NET, PCRE, and other engines.
- The performance warning is a heuristic and does not detect every ReDoS risk.
Privacy: Selected files and conversion or analysis results are processed in your browser and are neither sent to nor stored on the Develop Tools server.