How to search for third party applications that offer extensions for Photos

Photos for Mac can use two kinds of extensions:

• Photos Project Extensions: These extensions let you create projects and order them from third party print services, see: Photos Project Extensions Are Here
• Photos editing Extensions: These extensions, provided by third party applications, let you call third party editors and save the results back to Photos, see: Photo Editing Extensions for Photos for Mac

Previously it has been difficult to search for applications providing extensions, but Photos 3.0 on High Sierra will take you to the App Store, when you view the installed extensions in Photos and click the "More ..." item at the bottom of the list.

For example, to see all Photos Project Extensions,click the "+" to the right of "Projects" in the sidebar and then click "More ..." at the bottom of the menu.

You can also enter directly these search strings into the search field of the Mac App Store:

• To see all Photos Project Extensions enter appex:com.apple.photo-project
• To see all Photos Editing Extensions enter appex:com.apple.photo-editing