This page lists tools that help you develop and debug websites and web apps. It's focused mostly on the tools developed and maintained at Mozilla, but we've listed other popular and useful tools under "More Resources".
The Toolbox provides a single home for most of the developer tools that are built into Firefox.
- Page Inspector
- View and modify the HTML and CSS for the selected element.
- Web Console
- Style Editor
- View and edit CSS styles for the current page.
- Network Monitor
- Inspect all the network requests that are made when a page is loaded, and how long they take to execute.
- Remote Debugging
Other DEVELOPER Tools
This section lists tools developed and maintained by Mozilla's Developer Tools team that aren't hosted in the toolbox. Most of these tools are built into Firefox, but the Firefox OS Simulator ships as an add-on.
- Responsive Design View
- See how your website or app will look on different screen sizes without changing the size of your browser window.
- Developer Toolbar
- A command-line interface to manipulate and work with the developer tools in Firefox, and buttons for quick access to the most commonly used tools.
- Error Console
- 3D View
- Also known as "Tilt", this provides a 3D visualisation of the current page.
- Firefox OS Simulator
- Run and debug your Firefox OS app on the desktop, without needing to use a real Firefox OS device.
This section lists resources which aren't maintained by Mozilla's developer tools team, but which are widely used by web developers. We've included a few Firefox add-ons in this list, but for the complete list see the "Web Development" category on addons.mozilla.org.
- DOM Inspector
- Inspect, browse, and edit the DOM of web pages or XUL windows.
- Web Developer
- Adds a menu and a toolbar to the browser with various web developer tools.
- Webmaker Tools
- A set of tools developed by Mozilla, aimed at people getting started with Web development.
- W3C Validators
- The W3C website hosts a number of tools to check the validity of your website, including its HTML and CSS.