How to install an extension in Safari on Mac: App Store steps, settings, and fixes

Safari comes built into every Mac, so it is probably the first browser you open. StatCounter put Safari at 7.83% of worldwide desktop browser use in October 2026, while Chrome had 66.98%. Those figures cover every desktop system, so they show the whole market, not just Macs. Other trackers report different numbers, so treat them as a rough guide.

This guide walks through the official route. You install extensions from the App Store, turn them on in Safari's settings, decide which websites they can use, and remove them when you are done. It also covers common problems and what to try first.

What you need before you install

Start with macOS. Apple's support page says to update macOS first, and that page is dated September 14, 2026. Extensions from the App Store need Safari 12 or later. Safari ships with macOS updates, so an updated Mac gets a current Safari too. For example, Safari 26 ships with macOS Sequoia 15 or later updates.

• Your macOS version. Choose Apple menu > About This Mac to see it.
• Your Safari version. Choose Safari > About Safari to see it.
• Whether you can sign in with an Apple Account. Apple may ask for one during the install.
• The kind of file you have. A download ending in .safariextz will not load.

Apple may ask you to sign in with your Apple Account during the install. If you cannot sign in, the install cannot finish. Keep your password and your two-factor code ready before you start.

Install the extension from the App Store

The menu item does not install anything by itself. Choosing Safari > Safari Extensions opens the App Store on the Safari Extensions page. The install happens there, when you click Get and then Install. Safari adds the extension after that step.

Use the App Store search box if you already know the name. Otherwise, browse the Safari category, which Apple describes as the place to find and add extensions. Each listing shows a Get button, or a price for paid extensions.

Some extensions cost money. If the developer name looks unfamiliar, read the description twice before you buy or install. A short description with vague claims is a reason to skip the listing and look for another one.

Turn an extension on or off in Safari Settings

After install, the extension lives in Safari's settings. Choose Safari > Settings, then click Extensions. Older releases call the window Preferences. Tick the checkbox beside the extension to turn it on. Untick it to turn it off without deleting it.

Safari can leave some extensions off for you. Apple says extensions that slow browsing are turned off when you first open Safari, until you turn them on. If an extension seems to do nothing, check that box before you try anything else.

Set which websites an extension can use

Many extensions read or change web pages. Safari lets you decide where each one runs. Select the extension in Safari > Settings > Extensions, then click Edit Websites. Each website you add gets its own access setting.

Here is a worked example. Say you install an extension that changes how news sites look. Add the news sites you read, and leave the rest of the web out of its list. Changing that list does not remove the extension. It only changes where the extension works.

Use extensions in Private windows

Private windows follow their own rule on newer Macs. On macOS Sonoma 14 or later, extensions that need website access are off by default in Private windows. Select the extension in the sidebar, then choose Allow in Private Browsing.

Profiles add another layer. Each Safari profile has its own Extensions tab, found in the Profiles tab. Extensions are off by default for new profiles, so you turn them on there for each profile you use.

Uninstall an extension you no longer need

To remove an extension, choose Safari > Settings > Extensions, select the extension, and click Uninstall. Custom extensions you made with Describe an Extension show Delete instead.

Off and uninstalled are not the same. Turning an extension off keeps it on your Mac. Uninstalling removes it. Apple also says that uninstalling on one device does not remove it from other devices.

Share extensions with your other Macs

Safari can share an extension across your Macs. Open Safari > Settings > Extensions, then select Share across devices at the bottom. The sharing option has its own requirements, so check them before you rely on it.

You need macOS Ventura 13 or later on each Mac. You also need the same Apple Account, iCloud set up for Safari, and two-factor authentication. Without those, sharing will not work.

Make your own extension with Describe an Extension

Apple added a way to build a small custom extension from plain words. Click the Page Menu button in the Smart Search field and choose Describe Extension. Enter what you want, click Next, then click Create.

You can then Try the extension, View it, Edit it, and Save it. This feature needs macOS 27 and Apple Intelligence. Apple says Apple Intelligence is not available in every language or region, and usage limits may apply.

Custom extensions cannot load remote content. They cannot use third-party services or access files on your Mac. Plan your idea around those limits before you start building.

Fix an extension that does not work

Start with the cheapest fix. Reload the page with View > Reload Page, or press ⌘R. Apple's troubleshooting page puts reloading first. Then work through the checks below, and change one thing at a time so you know what helped.

1. Reload the page with View > Reload Page or ⌘R.
2. Update macOS. Apple notes that Safari 26 ships with macOS Sequoia 15 or later updates.
3. Turn extensions off one at a time in Safari > Settings > Extensions, and reload the page after each change.
4. Update the extension itself from the App Store.
5. Under Websites settings, check whether a content blocker needs to be turned off.

If the problem stays, report it. After reloading, click the Page Menu button in the Smart Search field and choose Report a Website Issue. Describe the problem, then click Report. This option appears in Safari 26 or later.

Common mistakes to avoid

• Expecting the Safari Extensions menu item to install the extension by itself. You still click Get and Install in the App Store.
• Stopping at Install. Click Open, follow the onscreen setup, then check the box in Settings.
• Downloading an old .safariextz file. Safari does not load it.
• Forgetting Private windows on macOS Sonoma 14 or later. The extension stays off there until you allow it.
• Skipping Edit Websites, then wondering why an extension does nothing on one site.
• Assuming an install on one Mac covers every Mac. Each Mac needs its own install, or you use Share across devices.

Older Safari and macOS versions

Menu names change between releases. Apple's current pages say Settings. Older Safari releases say Preferences, so the path becomes Safari > Preferences > Extensions. Read the menu on your own screen before you follow a path.

WebKit says Safari 27.0 was released on September 17, 2026. Its web extension notes add reporting for uncaught JavaScript exceptions and unhandled promise rejections. These changes mostly matter to people who write extensions, not to people who install them.

What to do after the install

Install one extension, turn it on, and test it on a site you visit every day. Once it behaves, add the next one. Keep the list short, so you know which extension to check when a page misbehaves.

Open Settings > Extensions again every so often. Remove anything you no longer use, and check the website access for anything new before you rely on it.