Regular expressions are powerful but notoriously difficult to write and debug. Our regex tester provides real-time pattern matching with live highlighting, helping you craft perfect regex patterns faster while avoiding costly production bugs caused by untested expressions.
🎯 Live highlighting - See matches instantly as you type
🔍 Capture groups - Visualize and inspect captured substrings
🚩 Flag support - Test global, case-insensitive, and multiline modes
📊 Match statistics - Count matches and see all captured data
💾 Pattern library - Common regex patterns for quick reference
🐛 Error detection - Helpful messages for invalid regex syntax
Start Simple, Then Refine
Begin with a basic pattern that matches your target, then gradually add constraints. Test at each step to understand how each modifier affects matching behavior. This iterative approach prevents overwhelming complexity.
Use Non-Capturing Groups
When grouping is needed for alternation or quantifiers but you don't need the captured value, use (?:pattern) instead of (pattern). This improves performance and keeps capture group numbering clean.
Test Edge Cases
Always test regex with edge cases: empty strings, maximum length inputs, special characters, and unicode. Production data rarely matches simple test cases, so comprehensive testing prevents bugs.
Avoid Greedy Quantifiers
Use lazy quantifiers (.*? instead of .*) when matching until a specific character. Greedy matching can cause unexpected behavior and performance issues with large strings or complex patterns.
Document Complex Patterns
Add comments explaining complex regex patterns in your code. Future you (and teammates) will struggle to understand /^(?=.*[A-Z])(?=.*[0-9]).{8,}$/ without context. Document business logic driving the pattern.
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Data Format Converter
Convert between JSON, YAML, and XML formats with real-time validation.