Build & Test Regular Expressions
Build and test JavaScript-compatible regular expressions with guided presets, live match highlighting, a pattern library, bulk testing, basic explanations, and JavaScript code export.
Start Building NowAdvanced Regex Builder & Tester
Patterns are tested with your browser’s JavaScript regular-expression engine. Regex syntax and behaviour can differ in other programming languages.
Regular Expression Pattern
Test Your Regex
Why Use Our Regex Builder
How It Works
Frequently Asked Questions
The tool combines guided presets, a pattern library, live JavaScript-based testing, bulk file testing, basic explanations, and code-snippet generation in one browser-based interface.
Testing uses your browser’s JavaScript regular-expression engine, and the code-export button creates JavaScript code. Other programming languages can use different syntax, flags, and supported features, so test the pattern separately before adapting it elsewhere.
The bulk tester can read local TXT or CSV files and test their lines against the current JavaScript-compatible pattern. Start with reasonably sized files because complex regular expressions or very large datasets can slow or freeze the browser tab.
Regex testing and file reading happen locally in your browser. This tool does not upload or store your patterns, test text, or selected TXT/CSV files on ToolCookie servers.