Stats File Viewer

There are a few possible causes of this.

1. Two copies of the app.

If you downloaded the free build from the website and bought from the App Store, there are two 3MF Viewer.app bundles registering the same extensions. macOS elects one. Please delete all copies, empty your trash and install again, either from file or download from App Store.

2. Another app winning the UTI

Sometimes other apps will be installed that will also declare the UTI for files. (e.g., anyone with .3mf files almost certainly has Bambu Studio, OrcaSlicer or PrusaSlicer installed, and those declare 3MF document types too, and XCode grabs a lot of formats.) If this is the case (e.g., a .3mf file continues to open with Bambu Studio please let me know.)

3. Extensions switched off

Check in: System Settings → General → Login Items & Extensions → Quick Look. You should also see the app you downloaded listed and turned on.

4. Stale QL cache

Open Terminal and type

qlmanage -r cache

Then try again.

If you are still having problems, please contact me for more help.

Apps that have a downloadable version: Download the .zip file and then extract the contents. Copy the .app folder in to your Applications directory.

Apps distributed through the Mac App Store: use the "View on the App Store" button on the app's page here, then click Get (or the price). This will be logged to your account, enabling you to download on any of your devices, and get free updates in the future.

Updates come through the Mac App Store and are free. If you have automatic updates on (App Store → Settings), they install themselves; otherwise open the App Store app and check the Updates section.

Yes. An App Store purchase is tied to your Apple Account, not to a machine — sign in to the App Store on any of your Macs and download it again at no charge. Purchases can also be shared with your family via Apple's Family Sharing.

Open the App Store app, make sure you're signed in with the same Apple Account you bought with, click your name in the bottom-left corner, and you'll find everything you own ready to download again — free.

Purchases and billing are handled entirely by Apple, so I can't issue refunds myself — but Apple makes it easy: sign in at reportaproblem.apple.com, find the purchase and choose Request a refund.

None. No analytics, no advertising, no tracking SDKs, no accounts — anything an app processes stays on your Mac, and nothing needs an internet connection to work. The full privacy policy is one short page.

Use the contact form and include:

• your macOS version ( → About This Mac)
• the app version (app's menu → About)
• what you were doing when it went wrong, and what you expected to happen

If a particular file triggers it, say so — don't try to attach it, I'll reply with a way to send it over. Every report gets read and answered.

Please do — a lot of what's in the apps started as a user suggestion. Send it via the contact form with a line or two about what you're trying to achieve (the why often matters more than the what).