Regex Tester Online — Free
Test and debug JavaScript regular expressions in real time. Match highlighting, replace mode, flags, and sample patterns included.
Open Regex Tester →Whether you’re validating email addresses, extracting phone numbers, cleaning up CSV data, or building a web scraper, a reliable regex tester saves hours of trial and error. Our tool runs the native JavaScript RegExp engine — the same one used in modern browsers and Node.js — so the results match exactly what your code will produce.
All processing happens locally in your browser. Your patterns and test data never leave your device. No signup, no upload, no server round-trips.
Features
- Real-time match highlighting — matches light up in yellow as you type
- Replace mode — test find-and-replace with
$1,$2backreferences - Flag toggles — click
g,i,m,s,uto enable flags - Sample patterns — one-click load for emails, URLs, IPs, dates, HTML tags, and more
- Match details — see match count and full match list with group breakdown
- 100% private — no data leaves your browser, ever
Common use cases
| Use case | Example pattern | Description |
|---|---|---|
| Email validation | [\w.+-]+@[\w-]+\.[\w.-]+ | Matches standard email addresses |
| Phone number extraction | (\d{3})[-.]?(\d{3})[-.]?(\d{4}) | Finds US phone numbers with dash/dot separators |
| URL matching | https?://[^\s)]+ | Matches HTTP and HTTPS URLs |
| IP address validation | \d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3} | Matches IPv4 addresses |
| HTML tag stripping | <[^>]+> | Finds all HTML tags for removal |
It’s completely free — no signup, no credit card, no hidden limits. Built for developers, data analysts, QA engineers, and anyone who works with text patterns.
Ready to test your regex?
No signup required. Open the tool and start testing in seconds.
Use the Regex Tester NowFrequently Asked Questions
What flags are supported in this regex tester?
All standard JavaScript regex flags: g (global match), i (case-insensitive), m (multiline), s (dot-all — lets . match newlines), and u (unicode — enables \p{} escapes for categories like \p{L}).
Can I test regex replace with this tool?
Yes. Switch to Replace mode and enter a replacement string. Use $1, $2, etc. for captured group backreferences. The tool shows the replaced text instantly.
Is my data sent to any server?
No. All regex testing happens locally in your browser using the built-in JavaScript RegExp engine. Nothing is uploaded or stored on any server. Your test data stays on your device.
Does it support lookahead and lookbehind?
Yes. The JavaScript RegExp engine supports positive lookahead (?=), negative lookahead (?!), positive lookbehind (?<=), and negative lookbehind (?<!). Test them all in our tool.
Is this regex tester really free?
Yes. No signup, no limits, no ads, no email required. Everything runs in your browser. It’s completely free to use, forever.