Test and debug regular expressions with live matching, explanations, and pattern examples.
( )/(\d+)\.(\d+)/ on 123.45 gives Group 0: 123.45, Group 1: 123, Group 2: 45Regular expressions (regex) are powerful pattern-matching tools but notoriously difficult to master. The Regex Tester provides a development environment for writing, testing, and debugging regular expressions with real-time feedback. Regex is used extensively in programming for text processing, validation, extraction, and transformation. Email validation, phone number formatting, data extraction, log analysis, and text search all use regex. Learning regex opens powerful text processing capabilities. Our Regex Tester features: live matching against test text (see matches highlighted in real-time), detailed explanation of regex pattern components, common regex patterns (email, phone, URL, date, etc.) as templates, replace functionality (find-and-replace using regex), and JavaScript regex flavor support. Developers learn regex by testing patterns. Programmers debug regex patterns when they don't match expected text. Data engineers use regex for complex text transformations. System administrators use regex for log file analysis. Students learn regex concepts through interactive testing. Build regex patterns incrementally, seeing matches updated in real-time. Error messages help identify pattern syntax issues. Common patterns (email, phone, etc.) serve as templates for custom patterns.
Regex is a pattern language for matching text. Characters, wildcards, and quantifiers define flexible search patterns.
Basic pattern: /^[^\s@]+@[^\s@]+\.[^\s@]+$/ Though complete validation is complex; the tool has templates.
. (any char), * (0+), + (1+), ? (0-1), [] (character class), () (group), | (or), ^ (start), $ (end).
Test against sample text and watch which parts match. Break complex patterns into smaller pieces and test individually.