Regex Tester
Test a JavaScript regular expression and inspect matching text and positions.
Ready. Processing happens on your device.
Maximum 2 MB per text file. CSV limits: 20,000 rows and 200 columns. Drop one supported text file onto the input.
How to use Regex Tester
- Type or paste your input, open a supported local file, or try the example.
- Choose the available options and select Run tool.
- Review the output, then copy it or download it.
What to expect
Matching runs in a worker with a timeout. Results stop at 1,000 matches; complex expressions may be cancelled.
Common questions
Does Regex Tester send my input to a server?
No. Processing runs in a browser worker. Files are read locally and downloads are created on your device.
What if the result is empty or an error appears?
Check the input format and options. A filter or extraction may legitimately return no matches. Invalid formats show an explanation, and expensive operations stop after five seconds so you can revise the input.