Regex Tester & Code Generator

Test regular expressions with live match highlighting, interactive cheatsheet, and code generators.

📂 Popular Patterns:
//
g
🔍 Live Highlight Preview
3 matches
💻 Code Snippet Generator
🔒 Processes locally in your browser — zero network transmission.

How the Regex Tester & Code Generator Works

The Regex Tester & Code Generator by DwellixTools is an interactive, browser-only tool designed for developers to write, test, debug, and implement regular expressions. By executing matching logic locally in your browser, this tool ensures that your test data and patterns are completely private.

You can input a regex pattern, toggle standard flags (Global, Case-Insensitive, Multiline, DotAll, Unicode), and immediately see all matching instances highlighted inside the Live Highlight Preview panel. Furthermore, you can copy pre-generated, production-ready code snippets to implement your regex in multiple languages including JavaScript, Python, Go, PHP, and Java.

Key Features

  • ⚡ Real-Time Highlight Preview: Renders matching strings instantly as you type, complete with distinct highlighting colors for adjacent matches and index information.
  • 💡 Interactive Cheat Sheet: A built-in sidebar of essential regex classes, quantifiers, and boundaries. Clicking any element automatically inserts it at your exact cursor position.
  • 📂 Popular Pattern Library: Built-in standard regex presets for quick-loading common validations such as Email address, URL, IPv4, Date, and Strong Password.
  • 💻 Dynamic Code Generator: Instantly translates your regex pattern and active flags into working copy-paste code snippets for five popular programming languages.
  • 🔒 Browser-Only Processing: Runs entirely client-side using the browser’s JavaScript RegExp engine. Your patterns and test strings are never sent to a server.

How to Use the Regex Tester & Code Generator

  1. Input Your Pattern: Type or paste your regular expression in the Regular Expression input. Do not include the starting and ending slashes.
  2. Toggle Flags: Hover over the active flags display (e.g. g) on the right side of the regex input field to check or uncheck flags like Case-Insensitive (i) or Multiline (m).
  3. Write Test Text: Enter your sample text inside the Test String area.
  4. Inspect Live Highlights: Scroll through the Live Highlight Preview section to verify matches and view detailed coordinates.
  5. Generate Code Snippets: Click the tabs in the Code Snippet Generator card to copy matching code for your backend or frontend projects.

Frequently Asked Questions (FAQ)

Is my test data or regex private?

Yes. The entire tool processes text locally in your browser using the JavaScript RegExp API. No network requests are made, and no text is transmitted, logged, or saved to our servers.

Which regular expression engine does this tool use?

This tool uses the standard ECMAScript (JavaScript) Regular Expressions engine built into your web browser. Most behaviors are identical to other engines (like PCRE or Python’s re), though advanced lookbehind features or non-standard syntax may vary slightly by browser engine.

Can I insert characters using the cheat sheet?

Yes. Place your cursor inside the regex pattern input field at the position you want to insert a character, and click any button in the Interactive Regex Cheatsheet sidebar. The selected token will be instantly inserted at the cursor position.