Online Regex Tester & Debugger (PCRE, JS) - Master Tools

Regex Tester Usage Example

Usage Steps:

1. Enter Regex - Input the regular expression pattern in the regex input field
2. Set Flags - Set regex flags (like g, i, m, etc.) in the flags input box
3. Select Pattern - Click "Common Patterns" to quickly select preset regex patterns
4. Input Test Text - Enter the text content to match in the test text area
5. Execute Test - Click the "Test" button to view matching results
6. View Results - Check highlighted matches and detailed match information

Features:

• Real-time Testing - Supports real-time testing and validation of regular expressions
• Syntax Highlighting - Match results are highlighted for easy viewing
• Match Details - Displays match position, capture groups, and other detailed information
• Text Replacement - Supports text replacement based on regular expressions
• Common Patterns - Built-in common regex patterns for email, phone, URL, etc.
• Flag Support - Supports global match (g), ignore case (i), multiline (m) and other flags

Use Cases:

• Data Validation - Validate email, phone number, ID card, and other formats
• Text Extraction - Extract specific format data from text, like URLs or hashtags
• Content Replacement - Batch replace content matching specific patterns in text
• Log Analysis - Extract key information from complex log files
• Code Refactoring - Use regex for batch code modifications and search-and-replace
• Data Cleaning - Clean and format irregular or unstructured data

Common Questions (Q&A):

1. Q: What can I use this regex tester for?
   A: Use it for validating emails, phone numbers, URLs, log extraction, replacement rules, and front-end or back-end form validation patterns.
2. Q: Why does a regex behave differently in another language?
   A: Regex engines differ in syntax, escaping, and flag support. Treat this tool as matching the JavaScript or PCRE-like behavior shown in the UI.
3. Q: How do I debug a pattern that does not match?
   A: Check flags, escaping, case sensitivity, multiline mode, whitespace, and then simplify the pattern step by step.