Regex Tester
Test regular expressions against text with real-time highlighting. Perfect for developers learning and debugging regex patterns.
About This Free Online Regex Tester
Our free regex tester lets you build and debug regular expressions and see exactly what they match in real time. Type a pattern and paste in your sample text, and the tool highlights every match as you edit, so you can refine your expression without guesswork. It supports the common flags such as global, case-insensitive, and multiline, and shows captured groups so you can confirm your pattern is pulling out the right pieces. Regular expressions are notoriously hard to get right, and a small change can break a pattern in surprising ways, so seeing matches update live makes learning and troubleshooting far quicker. It uses the JavaScript regex engine, the same one that runs in browsers and Node.js. Everything runs locally, so your patterns and test data stay private, with no signup required.
Features of Our Regex Tester
- Real-time regex matching with highlighting
- Support for global, case-insensitive, and multiline flags
- Shows match count and match details
- Copy regex pattern to clipboard
- 100% private — browser-only processing
How to Use the Regex Tester
The Regex Tester works right in your browser — no signup, no installation. Follow these steps:
- Enter your regex pattern in the pattern field.
- Type or paste your test text in the text area.
- Toggle flags (g, i, m) as needed.
- Matches are highlighted in the text area. Match count is shown below.
Frequently Asked Questions About Regex Tester
What regex flags are supported?
Three flags are supported: g (global — find all matches), i (case-insensitive), and m (multiline — ^ and $ match line boundaries). These are the most commonly used flags in JavaScript regex.
Does this support all regex features?
This tester uses JavaScript's native RegExp engine, so it supports all JavaScript regex features including character classes, quantifiers, groups, lookaheads, and Unicode properties. Some advanced features like lookbehinds may not work in older browsers.
Why Choose the Regex Tester?
Developers and power users need tools that are exact and private. The Regex Tester runs its logic locally in your browser, returns results instantly, and never transmits your input — handy when you are working with keys, hashes, or data you would rather not paste into a remote service.