Regex Tester
Test, debug, and validate regular expressions with live highlighting, capture groups, replace preview, pattern analysis, and a preset builder — all local to your browser.
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What is Regex Tester?
Regex Tester is a free, browser-based tool in our Developer Tools collection. Test, debug, and validate regular expressions with live highlighting, capture groups, replace preview, pattern analysis, and a preset builder — all local to your browser. Because every step runs locally in your browser using JavaScript and WebAssembly, your files never leave your device — there is no upload, no server, and nothing stored after you close the tab.
How to use Regex Tester
- Open the tool above — no account or install needed.
- Add your file or input directly in your browser.
- Adjust any available options to fit what you need.
- Run the tool and download the result instantly.
Why use our Regex Tester tool?
- 100% private — processing happens on your device, not a server.
- Free with no limits — no sign-up, no watermarks, no file-size caps.
- Works offline once the page has loaded.
- Cross-platform — runs on any modern browser, desktop or mobile.