Expert's Rating
Our Verdict
PowerPhotos is an extremely useful addition as an enhancement for any Photos user trying to perform tasks that fall outside of Photos restricted purview.
While Photos is streamlined and zippy compared to iPhoto, its stripped-down approach can be confusing. PowerPhotos takes some of the shock out of Photos for OS X by helping bridge the gap between old and new. Fat Cat Software’s app offers assistance in migrating iPhoto libraries, managing (and merging) multiple Photos libraries, and offers a different way of viewing images and videos. It’s more flexible, to be sure.
When launched, PowerPhotos shows—under an Operations listing—Migrate iPhoto Libraries, which can also be selected later from the File menu. This lists all iPhoto libraries that it can find via Spotlight; you can add others manually.
The migrate operation lets you manage creating Photos-compatible libraries without babysitting the Photos app, and shows progress and errors. It can also migrate several libraries from the same interface instead of requiring multiple iterations of quitting and launching Photos with the right key held down.
In the 1.1 update, the app added the ability to merge Photos libraries as well as copy images and albums to existing or new Photos libraries. This dramatically expands its utility; its price also was bumped from $20 to $30, but it bundles a fully licensed copy of its predecessor, iPhoto Library Manager, which can merge iPhoto and Aperture libraries before you import them into Photos. (Existing owners of that product can upgrade for $15.)
Merging libraries and finding duplicates
Once you have Photos libraries migrated from iPhotos or created anew, you can use PowerPhotos’ Merge Libraries and Find Duplicate features, which employ different strategies through a very similar interface. Those waiting to upgrade to Photos until a point at which they could merge or at least rationalize various libraries can now take the plunge.

The Merge Libraries options are elaborate, allowing fine control over the results.
Select Library > Merge Libraries, and an item appears in the left navigation bar under Operations. Select it and you can then drag libraries in the Photo Libraries list into the Choose Source Libraries area. (At this writing, the text in that area is incorrect.)
In the next step, you choose whether to merge into an existing library or create a new one as the product of the merger. You can then, in step 3, select duplicate handling, which will de-duplicate within a single library (described below) and across multiple merging libraries.

The preview during Merge Libraries lets you inspect which duplicates were found.
Finally, step 4 offers merger-specific options, which includes a few general items, like merging albums with the same name, and one critical radio-button choice: whether to import originals or edited versions. If you select the former, any edits made in Photos aren’t copied, only the original image as imported; select the latter, and originals are copied for unedited images and videos, but for Photos-edited images, only the resulting JPEG stored in Photos is copied over.

When a merge is complete, PowerPhotos offers a summary of what it did.
You can click Preview to have it run an analysis before completing the operation, and see both the resulting library and any duplicates found.
Another version 1.1 feature lets you take selected photos or albums and drag them into another library. This doesn’t remove them from the original—that’s a separate step you have to take *within* Photos. So if you want to split a library into multiple libraries, you should use Photos to create albums, then use PowerPhotos to duplicate those albums into new or existing libraries, and finally delete them via Photos from the original library.
If you don’t have libraries to merge (or split), you can use the Find Duplicates feature to reduce the size of your corpus and remove the detritus of year’s past—duplicate imports you may have made accidentally.
I apparently have 43,169 photos in my master Photos library, and I hadn’t spotted many duplicates in my perusal. PowerPhotos found over 1000! If you have multiple Photos libraries, you can scan across them, too.
The app gives you several choices for deciding how to let it identify duplicates (whether in Find Duplicates or Merge Libraries), including excluding hidden photos, images marked with “duplicate” in the keyword field, and photos that it’s already placed in a special album. Comparisons can be based on the content of an image (Exact Match), which looks for byte-for-byte identical versions of either the original image or any modified version you’ve stored. Or, you can opt for filename and date, which includes minor variations in filenames commonly used with duplicates. (Merge Libraries uses these criteria, but also adds an option to remove duplicates while merging, and to use additional metadata criteria to sort out which image should be kept in the merge operation.)
Even with my huge library and using exact matches, it only took about 20 minutes on a 2014 Mac mini while I continued to work on tasks in other apps. Once the pass is complete, you can review pairs or multiples of images and make sure your matches are correct. If not, you can switch which image in a set you want to be the “keeper,” or discard the match entirely, among other options.
When you’re done reviewing and click Apply, instead of deleting the files or moving them to the trash, the images are placed by default into a special duplicates album, which you can then review in Photos to dump into the trash.
Library management
While you might use Find Duplicates once or rarely, the ability to easily review and switch among multiple Photos library is a must-have feature for many users, based on the email we’ve received at Macworld. Some iPhoto users set up multiple libraries, one per year, or with other divisions that they want to maintain and have access to. PowerPhotos can’t overcome iCloud Photo Library’s limit: one Photos library is a master to which iCloud syncs.
With a Photos library selected, PowerPhotos lets you select Moments as items in its navigational column. Albums and Smart Albums are also shown. But where it shines compared to Photos is with its list view and in a middle ground for search between Photos very basic option and Smart Albums.
Click the list icon at upper right, and PowerPhotos shows a thumbnail that can be sized from tiny to enormous, and then a host of associated data, allowing easier scanning through and sorting. By default, it just shows a few items, like Title and Date. But pop into the View > Show Columns items list, and you can add Description, Place, Faces, Size, and more.
This works well in association with its find feature. Type in a word or more, and PowerPhotos searches across all of an image’s file data and metadata. But then you can opt to broaden to search across all libraries the app is managing, and narrow to match that text only across Title, Filename, Keywords, Faces, Place, Description, and Moment. While you can achieve this with a single library using Smart Albums in Photos, it’s not interactive nor can it provide the compact density of a detailed list.
Bottom line
PowerPhotos is an extremely useful addition as an enhancement for any Photos user trying to perform tasks that fall outside of Photos restricted purview. With the addition in Photos 1.1 of merging libraries and copying images and albums across libraries, it’s become invaluable for long-time iPhoto and Aperture users trying to make sense of moving forward. And its utility features—including identifying duplicates, multi-library and metadata searching, and other bits and pieces—show the ongoing worth of having it your arsenal.