What is the Regex Tester?
A Regular Expression (Regex) Tester evaluates complex search patterns against test strings. It helps developers safely build and debug patterns for form validation, data extraction, and search algorithms.
Key Features
Real-time pattern matching
JavaScript RegExp Engine
Syntax highlighting
Global & Case-insensitive flags
Extract capture groups
How to use the Regex Tester
- Type your regular expression in the top input field.
- Paste your test text in the main body.
- Toggle flags like global (g) or case-insensitive (i).
- Matches will highlight instantly.
Examples
Input
Pattern: ^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$
String: test@example.com Output
Match Found: test@example.com
Common Errors & Troubleshooting
Unescaped Special Characters
Characters like . * + ? ^ $ ( ) [ ] { } | \ are special in regex and must be escaped with a backslash if you want to match them literally.
Pattern: google.com (Matches googleXcom) Fix: google\.com
When should you use this tool?
- Building email or password validation rules.
- Extracting specific data (like phone numbers) from large texts.
- Debugging a regex that is causing infinite loops.
What's the difference?
Regex
Powerful, complex pattern matching for deep text analysis.
Glob Patterns
Simpler pattern matching typically used for file path routing (e.g., *.js).
Tool Comparison
| Feature | ByteUtils |
|---|---|
| Live Highlighting | |
| Flag Toggles (g, i, m) | |
| Capture Groups | |
| Client-side Evaluation |
Frequently Asked Questions
Which regex engine does this use?
It uses the native JavaScript RegExp engine in your browser.
How do I extract capture groups?
Wrap your pattern in parentheses (). Matches will be grouped automatically.
Privacy First
All processing happens directly in your browser. Your data, payloads, and files are never uploaded to our servers or tracked.
Tool Information
- Category: text
- Runs in Browser: Yes
- Requires Login: No
- Mobile Friendly: Yes