Regex Tester Tool
About Regex Tester
Real-time regex testing (supports g / i / m). Input expression and text to see highlighted matches and counts.
AI Assistant Tip
Free users are limited to 30 uses per day.
How to test Regex?
- 1Enter your regular expression in the top input box (without surrounding slashes).
- 2Select flags like g (global) or i (case-insensitive) on the right.
- 3Type your test string into the textarea.
- 4Matching results will be highlighted in real-time below.
Regex FAQ
What regex engine is used?
This tool uses the native JavaScript RegExp engine, which is standard in all modern browsers.
What do the g, i, m flags do?
g enables global search; i makes the matching case-insensitive; m allows ^ and $ to match start/end of lines.
Practical Regex Scenarios
- Input Validation: Test patterns for email, phone numbers, and custom formatted IDs.
- Data Extraction: Verify logic for pulling URLs, dates, or IP addresses from messy logs.
- Code Auditing: Debug complex patterns used for static analysis or content replacement.
- Data Scrubbing: Test search-and-replace or split logic on small samples before large-scale processing.
Technical Details: JavaScript Regex Engine
This tool directly invokes the built-in regex engine of your browser's core (such as V8 or SpiderMonkey). This means results are 100% identical to what you'd experience in Node.js or modern web environments. We've optimized the real-time feedback loop with debouncing to minimize UI lag. For added value, we've integrated advanced AI capabilities that can translate cryptic regex into clear explanations, lowering the barrier for complex pattern debugging.