Regex Tester — Free Online Tool
Test regular expressions with live match highlights
How to use this tool
- [01]Enter your regular expression pattern, including any flags (g, i, m) you need.
- [02]Paste or type sample text into the test area below.
- [03]Matches highlight live in the text, with capture groups broken out individually so you can verify extraction, not just whether it matches.
About this Regex Tester
The Regex Tester runs your regular expression against sample text using JavaScript's native regex engine — the same engine your code will actually use if you're testing a pattern meant for a JS or TypeScript project — and highlights every match directly in the text as you type, rather than making you run the pattern separately to see results. Capture groups are broken out individually below the highlighted text, which matters for patterns where you're extracting specific pieces (a date's year, month, and day, for instance) rather than just checking for a match.
Because regex behavior varies slightly between engines — JavaScript, Python's re, and PCRE each handle certain edge cases like lookbehind support or named-group syntax a little differently — a pattern tested here is guaranteed to behave correctly in JavaScript specifically; double-check engine-specific syntax before assuming identical behavior elsewhere.
Common uses include validating a pattern before committing it to form validation code, debugging why a regex isn't matching expected input (often down to an unescaped special character or incorrect quantifier), and extracting structured data like emails, URLs, or dates from unstructured text using capture groups.
All matching happens in your browser as you type — the pattern and test text aren't sent anywhere.
Our Regex Tester is completely free to use with no signup required. For this tool, processing runs in your browser — your files and data stay on your device and are not uploaded to our servers.
Whether you are a developer, designer, student, or business owner, this tool is designed to save you time and make your workflow more efficient. Bookmark this page to access it whenever you need it — it will always be free.
Frequently asked questions
Is the Regex Tester completely free?
Yes, the Regex Tester is 100% free to use with no hidden charges, no subscription, and no signup required. Simply visit the page and start using it immediately.
Does this tool upload my files to a server?
No. Everything runs entirely in your browser using JavaScript. Your files, text, and data never leave your device and are never sent to our servers. This makes it completely private and secure.
Does the Regex Tester work on mobile?
Yes, the Regex Tester is fully responsive and works on all devices including smartphones, tablets, and desktop computers. It works on Chrome, Firefox, Safari, and Edge browsers.
How accurate is this tool?
Our Regex Tester uses industry-standard algorithms to ensure accurate results every time. It has been tested extensively across different browsers and devices to ensure consistent and reliable output.
Will a regex that works here behave the same in Python or another language?
Not always — this tester uses JavaScript’s regex engine specifically. Most common syntax is shared across engines, but features like lookbehind assertions and named group syntax can differ, so verify engine-specific behavior before relying on it elsewhere.
Why isn’t my pattern matching text I expect it to?
The most common causes are an unescaped special character, a quantifier that’s greedier or stricter than intended, or forgetting the global flag when you expect multiple matches instead of just the first one.
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