How to run Safari 4 beta and Safari 3 on the same mac

Apple dropped the first public beta release of Safari 4 today, and installing it overwrites the old version of Safari as well as the system Webkit frameworks. This means it’s not possible to run the current Safari 3 release and the beta on the same system. That is, not possible without some fiddling.

Here’s a quick how-to get both Safari 3 and 4 beta running on the same system. You will need to use the terminal for part of this, and we will download an older copy of Webkit, which is Apple’s development builds of Safari.

(It’s a bit confusing, but there are Webkit frameworks, which Safari uses to render web pages, and a Webkit application, which is what Apple uses to test development versions of the Webkit frameworks.)

I am not responsible if this blows up your computer, causes your pants to spontaneously fall to your ankles causing you to flash your junk to the world, provokes fire to shoot out of your fingertips, etc.. Caveat nerd!

1. Download and install the Safari 4 beta. You’ll need to reboot after the install because of the system framework changes.
2. After rebooting, rename the new Safari.app in your Applications folder to Safari4.app.
3. Download the Webkit build from 11/22/2008.

   Safari 3.2.1 was released on 11/24/2008 so I’m guessing this build is very close to that version.

4. Mount the Webkit disk image and copy the Webkit.app application to your desktop.
5. Rename Webkit.app to Safari3.app and move it to your Applications folder. In your Applications folder you should now have Safari3.app and Safari4.app.

   The Safari 4 installer backs up the previous version as an invisible file located at /Library/Application Support/Apple/.Safari4PreviewArchive.tar.gz. We need the original Safari.app bundle as the old version of Webkit we downloaded will not work with the new Safari 4 bundle.

6. Launch the terminal and change directories:

   cd "/Library/Application Support/Apple/"

7. Expand the backed up archive: tar -zxvf .Safari4PreviewArchive.tar.gz. This creates a few new folders in the current directory: Applications, System, and usr.
8. You can now copy the old Safari.app which is now available the the newly created Applications folder to the top-level /Applications folder. You can either use the terminal (running the command cp -R "/Library/Application Support/Apple/Applications/Safari.app" /Applications/) or by navigating to Library » Application Support » Apple » Applications in the Finder and copying the Safari application bundle that way.

After all of this, you should have Safari.app, Safari3.app, and Safari4.app in your top-level Applications folder. To run the Safari 4 beta launch Safari4.app, and to run the original Safari 3 launch Safari3.app. You may be able to run Safari.app as well (I was able to launch it and it identifies itself as Safari 3.2.1) but I wouldn’t recommend this as it uses the system webkit frameworks, which were replaced when Safari 4 was installed.