Regex Tester
Test JavaScript regex with live match highlighting & groups.
See how it works
Watch a quick simulation of this tool in action — no file needed.
How to use Regex Tester
Follow these steps — everything happens instantly in your browser.
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Step 1. Enter your regex pattern (without the surrounding slashes).
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Step 2. Toggle the flags you need (g, i, m, s, u, y).
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Step 3. Type or paste the text to test against.
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Step 4. Review the highlighted matches and the per-match group table.
Why use this tool
Private by design
All processing happens locally in your browser. Open DevTools → Network and you'll see zero file uploads. Ever.
Instant
No upload wait, no queue, no server round-trip. Results appear the moment you drop a file.
Free & unlimited
No accounts, no watermarks, no daily caps. Use it as many times as you like, forever.
Works everywhere
Desktop, tablet or phone — every tool is responsive and installable as a PWA for offline use.
Frequently asked questions
Everything you might want to know about regex tester.
JSON Formatter
Beautify, minify and validate JSON — 100% in your browser.
URL Encode / Decode
Percent-encode or decode URLs and query strings — locally.
Base64 Encode / Decode
Convert text to and from Base64 — Unicode-safe, no uploads.
Markdown Preview
Write Markdown and see the rendered HTML live — side by side.