Running Safari Technology Preview Side by Side with Safari

This article explains how Safari Technology Preview operates alongside the standard Safari web browser on macOS. In short, yes, you can run both browsers simultaneously, as Safari Technology Preview functions as a completely independent application with its own isolated local data, caches, and settings, making it safe for testing and everyday use without disrupting your primary browsing environment.

Independent Application Execution

Safari Technology Preview is designed by Apple to be a standalone application. Installing it does not overwrite or replace the standard Safari browser that comes pre-installed on your Mac. You can launch both browsers at the same time, keep both icons in your Dock, and run web applications in each without causing system conflicts.

Local Data and Profile Isolation

Safari Technology Preview maintains its own separate directory in your Mac's system files. While standard Safari stores its data in the ~/Library/Safari folder, the preview version uses ~/Library/SafariTechnologyPreview. Because of this separation, the two browsers do not share local data.

The following elements are completely isolated between the two browsers:

  • Cookies and Website Data: Logging into a website on Safari Technology Preview will not log you into that same website on standard Safari.
  • Local Storage and IndexedDB: Web applications storing data locally on your machine will have separate databases for each browser.
  • Caches: Temporary internet files and cached assets are stored independently, making the preview browser ideal for web developers testing site changes.
  • Settings and Preferences: Changes made to the preferences in Safari Technology Preview—such as default search engines, developer menu toggles, or privacy settings—will not affect your standard Safari configuration.
  • Extensions: Web extensions are managed separately. You can enable or disable specific extensions in the preview build without altering your setup in the main browser.
  • Browser Profiles: If you use the Profiles feature (introduced in Safari 17), profiles created in Safari Technology Preview remain isolated from the profiles in standard Safari.

The Exception: iCloud Syncing

While local data and profiles are strictly isolated, Safari Technology Preview is still integrated with your Apple ID and iCloud by default. This means that cloud-synced data will appear in both browsers.

Automatically shared iCloud data includes:

  • Bookmarks and Favorites
  • Reading Lists
  • iCloud Tabs
  • Browsing History
  • iCloud Keychain (Saved Passwords)

If you want total isolation for testing purposes, you can simply use Private Browsing within Safari Technology Preview, or create a dedicated testing profile within the browser to prevent history and cookie cross-contamination.