Runs in your browser · inputs stay on your device
Regex Tester
Test JavaScript patterns with highlights, capture groups and a replacement preview.
0 matches shown (maximum 1,000)
Contact hello@example.com today.
Match positions and capture groups
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JavaScript regex syntax. Runs in a disposable worker with a timeout. Match positions are zero-based UTF-16 offsets.
How to use Regex Tester
Enter your inputs above, choose the available mode, and review the results. Copy or download options appear where supported. These tools process your inputs in your browser.
Frequently asked questions
Are my inputs uploaded?+
No. These tools process entered text, numbers and selected files locally in your browser. Invoice templates are saved on your device only when you explicitly choose to save them.
Can I use this tool for free?+
Yes. No account is required. Estimates depend on your inputs and the assumptions explained on this page.