Use the Safari Develop menu
If you’re a web developer, the Safari Develop menu provides tools you can use to make sure your website works well with all standards-based web browsers.
If you don’t see the Develop menu in the menu bar, choose Safari > Preferences, click Advanced, then select “Show Develop menu in menu bar.”
See the table below for a description of the commands in the Develop menu.
Open Page With
Opens the displayed webpage using another web browser installed on your computer, as listed in the submenu.
Changes the User Agent header included with outgoing HTTP requests. Use this option to “spoof” the web server into thinking that you’re using a different browser, operating system, or version of Safari, so you can investigate whether the server is providing different content under varying conditions.
Shows devices with JSContexts that you can inspect remotely.
Enter Responsive Design Mode
Responsive Design Mode provides a unified interface for designing web experiences across various screen sizes and orientations. Use this option to quickly preview your web content with a variety of different screen sizes (including those for Apple devices and custom viewports) and User Agents. For more information, see Simulate Apple devices.
Show Snippet Editor
Lets you quickly test small fragments of HTML and CSS without opening an entire webpage.
Show Extension Builder
Allows you to build and package .safariextz-style Safari extensions. Use Xcode to build Safari App Extensions to distribute through the Mac App Store.
Show Web Inspector
Web Inspector provides a unified interface to inspect, debug, and improve web content. Use it to view the resources, timelines, source code, debugger, and console messages for web content. For more information, see Examine webpage elements and activity.
Show Page Source
Shows the HTML source code for the main frame of the displayed webpage.
To search the source code, click anywhere in the code, press Command-F, then enter a word or phrase in the search field that appears in the Source Code pane.
Show Page Resources
Shows a list of web content resources, such as documents, style sheets, scripts, images, and fonts.
Start Timeline Recording
Start Element Selection
Allows you to select any DOM element on the current webpage with a light blue selector box.
Empties the network cache and other Safari caches.
Retrieves a subresource from the web server each time the subresource is accessed, rather than using a cached copy.
Shows the alternate content for images instead of the images themselves. This is useful for ensuring your webpage has appropriate alternate content.
Ignores all CSS styles. This is useful for investigating some types of page layout problems on your website. If you have a style sheet set in the Advanced pane of Safari preferences, it continues to be used.
Disables all extensions. Installed extensions are listed in the Extensions pane of Safari preferences.
Disable Site-specific Hacks
Turns off special-case Safari code that works around issues with certain websites, so that developers of those websites can test solutions to the issues.
Disable Local File Restrictions
Treats all files on your Mac as being of the same origin, so that the files can access each other’s content via scripting or XHR. This enables a copy of a website on your Mac to function as if it were on a web server with a single origin.
Disable Cross-Origin Restrictions
Enables the AppleScript command
Allow Remote Automation
Allows you to perform automated testing using WebDriver.
Allow Unsigned Extensions
Allows you to develop and test extensions without a development certificate.
Get Safari Technology Preview
Takes you to the download page where you can get an early look at upcoming web technologies in macOS and iOS.