Gemini 2 alternatives, and when a duplicate finder is worth paying for
Gemini finds duplicates on a subscription. Here is what duplicate finders can and cannot know, and the free checks that cover most of it.
Duplicate finders are sold as if finding identical files were difficult. It is not, and knowing why changes what you should pay for. The hard part is deciding which copy is the original, and no program can know that.
What a duplicate finder is really doing
Two files are identical if their contents hash to the same value. That is the entire algorithm, and macOS ships the tool for it. This finds identical files in a folder and groups them:
find ~/Downloads -type f -size +1M -exec shasum -a 256 {} + \
| sort | uniq -w64 -DEvery line printed is a file whose contents match another line in the same group. Point it at Downloads, Documents or an external drive. It is slow on very large folders because it reads every byte, which is also true of the paid apps.
What you are paying for, honestly
- Similar rather than identical. Photos that differ by a crop or a compression pass do not hash the same. Finding those needs image comparison, and that is genuinely hard work you cannot script in one line.
- Choosing which copy to keep. Newest, largest, the one outside the Trash, the one not inside a Photos library. A good interface makes that decision fast and reversible.
- Not breaking a library. Photos and Music keep their own databases, and deleting files out from under them by hand causes damage a duplicate finder is built to avoid.
That third point is the one worth the money if your duplicates are inside a Photos library. It is also the reason to be careful with any tool that offers to clean one.
The part that is oversold
On most full Macs, duplicates are not where the space went. They are visible and satisfying, so they get attention, while the actual problem is usually one of a short list: old device backups, developer output, a video project, or a cache that ran away. Before subscribing to anything, find out whether duplicates are even in your top ten:
du -xh -d 1 ~ 2>/dev/null | sort -h | tail -15If that ends with a 40 GB folder you had forgotten about, deal with that first. The order to free 100 GB sets out which categories are worth checking in which sequence, and duplicates sit lower down it than people expect.
The alternatives
| Option | Cost | Finds similar images | Notes |
|---|---|---|---|
| Gemini | From $1.95 per month | Yes | Polished, handles Photos libraries carefully |
| shasum in Terminal | Free | No | Exact duplicates only, one command |
| Photos' own duplicates album | Free | Yes, for photos | Built into recent macOS, inside the library |
| Free Mac | Free to scan | No | Finds the large folders first, which is usually the real problem |
The free route for exact copies is covered step by step in finding duplicates without paying. For photographs specifically, the duplicates album built into Photos handles the library safely and costs nothing.
Common questions
How much does Gemini cost?
From $1.95 per month, checked on macpaw.com on 9 September 2026, with a free download to try first. The current version is 407, released 4 September 2026, and it requires macOS 10.10 or higher.
Can I find duplicate files on a Mac for free?
Yes, for exact duplicates. A single find and shasum command groups files with identical contents, and Photos has a built in duplicates album for images. What free tools do not do is find visually similar photos that are not byte identical.
Are duplicate files usually why a Mac is full?
Rarely. Old device backups, video projects, developer output and runaway caches are almost always larger. Duplicates are worth clearing, but check the largest folders on the disk first so you are not subscribing to solve a small part of the problem.
Is it safe to delete duplicates inside a Photos library?
Not by hand. The library keeps its own database and removing files underneath it causes inconsistencies. Use the duplicates album inside Photos, or a tool that is built to work with the library, and leave the folder contents alone.