Regex Tester
Test a JavaScript regular expression and inspect matches and capture groups. Free, with no signup or usage-count limits.
Free · No signup · No watermark · On-device processing
Use the tool
How to use Regex Tester
- Paste the text to search.
- Enter a pattern without slash delimiters and choose JavaScript flags such as gi.
- Run the test and inspect match text, offsets and capture groups.
Understand the input and output
Enter a pattern without surrounding slash delimiters and select JavaScript flags. Matches show zero-based UTF-16 offsets and captured groups. Matching runs in a separate worker so a pathological pattern can be stopped.
This is the JavaScript regex engine, not PCRE or Python. A time budget stops expensive patterns and a preview shows at most 1,000 matches.
Privacy and browser support
Your input is handled in this browser tab. Selected files and entered text are not sent to Varento Tools by this tool. Some specialized libraries load only when needed. A browser with JavaScript and sufficient device memory is required. Read our local-processing explanation.
Related tools
Frequently asked questions
Is this tool free without daily usage limits?
Yes. Varento Tools has no signup, accounts, usage-count caps, paywalls or watermarks. Device memory, format support and browser restrictions can still limit technically demanding files.
What happens when a pattern is too slow?
The worker is terminated after a short time budget. The page remains usable; simplify the pattern or test a smaller input. This protects responsiveness rather than guaranteeing every pattern finishes.
Is my input uploaded?
No. This tool processes your input in the current browser tab and does not send it to a processing server.
What are the practical limits?
This is the JavaScript regex engine, not PCRE or Python. A time budget stops expensive patterns and a preview shows at most 1,000 matches.