How Safari Syncs Extensions Across Your Apple Devices

This article explains the mechanics and usage of the "Sync Across Devices" feature in the Safari web browser. By leveraging iCloud and the App Store's app-matching database, this toggle allows users to seamlessly view, download, and manage compatible Safari extensions across their Mac, iPhone, and iPad without having to manually search the App Store on each individual device.

The Underlying Mechanism: iCloud and Universal Apps

The "Sync Across Devices" feature relies on two core Apple technologies: iCloud and App Store developer linking. Because macOS, iOS, and iPadOS operate on different system architectures, a Mac Safari extension cannot simply be copied over to an iPhone. Instead, developers create separate versions of their extensions for each operating system and link them together in the App Store backend as a single universal offering.

When you turn on the sync toggle, Safari uses your iCloud account to broadcast a list of your currently installed extensions to your other Apple devices. When a receiving device gets this list, it checks the App Store database to see if the developer offers a compatible version of that specific extension for its operating system.

How Users See and Install Matching Extensions

Once Safari identifies that an extension installed on one device has a compatible counterpart for another, it updates the Extensions menu interface to let you install it directly.

On a Mac:

  1. Open Safari, click Safari in the menu bar, and select Settings (or Preferences).
  2. Click the Extensions tab.
  3. Ensure the Sync across devices checkbox at the bottom of the window is selected.
  4. Look at the left sidebar. Below your currently installed extensions, a section labeled From Other Devices will appear.
  5. This list displays compatible extensions currently residing on your iPhone or iPad. Clicking the Get or iCloud download button next to an extension immediately installs the macOS version from the Mac App Store.

On an iPhone or iPad:

  1. Open the Settings app and navigate to Safari (or Apps > Safari in iOS 18 and later).
  2. Tap Extensions.
  3. Turn on the Sync Across Devices toggle.
  4. Scroll down to the On Other Devices section.
  5. Here, you will see extensions installed on your Mac or other iOS devices. Tapping the iCloud download icon next to an extension automatically downloads the iOS or iPadOS version in the background without requiring you to open the App Store app.

Automatic State Synchronization

Beyond simplifying the installation process, the toggle also synchronizes the active state of your extensions. Once a matching extension is installed on multiple devices, enabling or disabling it on one device will automatically turn it on or off on all other synced devices. This prevents you from having to configure your active extensions repeatedly on different screens.

System Requirements for Syncing

For the "Sync Across Devices" toggle to function properly, the following conditions must be met on all participating devices:

  • Devices must be running at least iOS 16, iPadOS 16, or macOS Ventura.
  • All devices must be signed in to the exact same Apple ID.
  • Safari must be enabled in your iCloud settings (Settings > Apple ID > iCloud > Show All > Safari).
  • Two-factor authentication must be turned on for the Apple ID.

Note that this feature only syncs the presence and active state of the extensions. If an extension requires a paid subscription or specific internal settings (like custom ad-blocking rules), those configurations are managed by the individual extension developer and may still need to be set up manually after installation.