21st September 2026
About seven in ten people using our offload app are on a Mac, so that is what this is about. TeraCopy for Mac 1.1, the build dated May 2025, and Stow 0.6.60. I have not tested the Windows versions and will not pretend otherwise.
I should say up front that we make Stow. It is free, and we have no plans to charge for it, but it is ours, so read this knowing that.
Why we set up a test at all
We wanted to know two things. How does each one actually work when you sit down with it, and does it hold up when something goes wrong.
You cannot answer that from feature lists, and you cannot answer it fairly by running one tool on one card and the other on another. So we made a lab card: a removable FAT32 volume laid out like a Sony card, with three 12 MB clips, the XML sidecar that sits beside each one, and the bits a camera leaves in its own folders. Both tools got that same card on the same Mac, on 20 and 21 September.
It is one card on one machine, so treat it as a hands-on comparison rather than a laboratory result. The conditions were the same for both, which is the part that makes it worth anything.
Everything I did with TeraCopy was on the free version, including the verification. You do not have to pay to check a copy.
The resilience test
The thing worth checking is whether a tool really looks at what it copied, or just trusts it. Plenty of software says it verifies and only compares file sizes, which will pass a file that has quietly gone wrong. We have compared a wider set of offload tools elsewhere, paid and free, if you want the longer view.
So after copying, we went into the destination and changed a single byte in the middle of one clip, leaving the file exactly the same size.
TeraCopy caught it. Eleven verified, one failed, the clip named, and the two checksums printed so you could see they did not match.
Stow caught it too. Seventeen of eighteen files verified, one corrupted, none missing, and the same clip named. It reads the copy back against the hashes it wrote at the time, which is also how it finds bit-rot on a drive you have not touched for two years.
Neither was fooled. That is the answer you want from both, and it is the reason I would be relaxed about either one on a real card.
TeraCopy also handled the card structure properly, which I was not sure it would. The whole folder tree came across untouched, sidecars and all. The two use different counting rules in their reports, so the totals are not directly comparable and there is nothing to read into one number being higher than the other.
Two things worth knowing if you are on a Mac. TeraCopy’s Mac build uses MD5 and is a universal binary, so it runs on Intel Macs as well as Apple Silicon. Stow’s Mac build is Apple Silicon only, so on an Intel Mac there is no decision to make. Stow uses XXH3-128 and writes its checksums into an MHL manifest, a published format other post software can read, rather than only into its own log.
Where they are genuinely different
TeraCopy copies to one place and tells you how that copy went. It does that simply and does it well. Copying to more than one destination in a single run is listed as a Pro and Business feature, so on the free version two drives means running it twice.
Stow is built around the end of a shoot day rather than around files, so it takes two drives in the same job and gives you one answer for the card instead of a list to read.
One thing it does that we lean on: it looks at where your copies have actually landed. In the test, every file copied and verified to both destinations, twelve out of twelve, and Stow still would not clear the card. Both destinations turned out to be on the same physical disk. Two copies, one drive, so one failure would have taken both. It stayed amber and told us to keep the cards.
That is not TeraCopy falling short. A file copier is told where to write and writes there. It was never asked to have an opinion about whether your two copies are independent. If you want the habit rather than the software, we have written separately about backing up camera cards safely.
So who wins
Nobody, and I do not think that is a cop-out.
TeraCopy is simple and solid. The free version will copy and verify a card perfectly well. Pro is $49.95 paid once, with no subscription, and if you want one tool that copies anything anywhere and checks it properly, it will not let you down. One thing to check first: on the day I looked, the licences on Code Sector’s purchase page were listed for Windows, so if you are buying for a Mac it is worth asking them.
Stow ends up in the same place on a shoot day and costs nothing. I think the interface is better, though I would, and I would rather you decided that yourself. The thing I would actually point at is that it changes. We shipped five updates in September. Some of that came from people writing in about their own cards and cameras: one user sent a screen recording of his A7 IV behaving oddly, and that turned into a fix. I cannot promise a turnaround on anything, but if something about it annoys you we would rather hear it than not.
If you are clearing cards on a Mac, it is free. Put it on your next job alongside whatever you use now and keep the one you prefer.