Test regular expressions in realtime — matches highlighted, groups captured, patterns explained.
Regex Tester is a free online tool that lets you test regular expression patterns in real-time with live match highlighting and plain-English explanations of each pattern component. It helps you build, debug, and understand regex patterns quickly. The tool highlights all matches in your test text as you type the pattern, providing immediate visual feedback. It also breaks down your regex into individual components and explains what each part does in plain English — making complex patterns understandable even for regex beginners. Regular expressions are one of the most powerful text processing tools available, but also one of the most difficult to master. This tool bridges the gap by providing instant feedback and clear explanations, helping you learn regex while you use it. Everything runs entirely in your browser using JavaScript regex engine. Your patterns and test text are never sent to any server, making it safe for testing patterns against sensitive data. There are no usage limits and no account required. Common use cases include building validation patterns for email, phone, and URL formats, extracting data from log files, creating search-and-replace patterns, testing patterns before using them in code, learning regex syntax through interactive experimentation, and debugging complex patterns. For related tools, check out the Case Converter for text transformations, or the Diff Checker for comparing text versions.