Regex Tester

Regular expressions (regex) are patterns that describe sets of strings. They are used across virtually every programming language for searching, matching, and manipulating text. A regex pattern can be as simple as a literal word or as complex as a multi-part expression with lookaheads, quantifiers, and capture groups. Developers use regex for tasks like validating email addresses, extracting data from log files, finding and replacing text in code editors, and parsing structured text formats. Learning regex is one of the most transferable skills in programming.

Enter a regex pattern in the pattern field and type or paste your test string below. Matches are highlighted in real time as you type, so you can see exactly what your pattern captures without running any code. The matches table shows each match along with its position in the string and any captured groups. You can adjust flags like g for global matching, i for case-insensitive matching, m for multiline mode, and s to make the dot match newlines. This tool uses JavaScript's built-in RegExp engine.

Some patterns come up frequently in development. Use \d+ to match one or more digits, \b\w+\b to match whole words, and ^.+@.+\..+$ as a basic email check. For extracting content between delimiters, try patterns like \(([^)]+)\) to capture text inside parentheses. Lookaheads like (?=.*\d) are useful for password validation rules. When building complex patterns, start simple and add complexity incrementally, testing each step with this tool to make sure the pattern behaves as expected before moving on. Once you have crafted your regex, use our Diff Checker to verify that your find-and-replace operations produced the expected changes. Our Word Counter can also help you analyze the text you are working with.