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Gander support

Setup steps, fixes for the common problems, and how to reach us.

Contact

Email info@ganderfinder.com. Include your macOS version, the Gander version (in the Gander menu, choose About Gander) and the kind of file you were previewing. Please don’t attach files that contain passwords or keys.

Set up Gander

  1. Install Gander from the Mac App Store.

  2. Open Gander once. Its window shows whether Quick Look is using it, and lets you choose which file types and Markdown extras it handles.

  3. In Finder, select a file and press Space.

Still seeing the standard preview? Turn on Gander in System Settings › General › Login Items & Extensions › Quick Look. The Gander window has a button that opens that page.

Fix common problems

Quick Look still shows the standard preview

  1. Make sure Gander is in your Applications folder. The Mac App Store installs it there.
  2. Open Gander once, so macOS registers its extensions.
  3. Go to System Settings › General › Login Items & Extensions › Quick Look and turn on Gander. The Open Quick Look Settings button in the Gander window opens that page.
  4. If another Quick Look app previews the same file type, turn it off on the same page.
  5. Select the file in Finder and press Space again.

A file type opens with the standard preview

  1. Open Gander and check that the switch for that file category is on.
  2. Check the supported file types. A file whose name or extension isn’t listed there gets the standard preview.

Finder thumbnails don’t change

  1. Finder caches thumbnails. Switch the folder to another view and back, or relaunch Finder: hold Option, Control-click Finder in the Dock and choose Relaunch.
  2. To clear the cache completely, run qlmanage -r cache in Terminal, then relaunch Finder.
  3. SQLite files, folders, MIDI, XIP and plain .gz files keep Finder’s own icon. That is expected.

“Your choices can’t be saved” appears in the Gander window

  1. Gander couldn’t write to its settings folder, so Quick Look keeps previewing every file type. Delete Gander, then reinstall it from the Mac App Store.

More answers

What is Gander?

Gander is a Quick Look extension for macOS, made by 65FN LLC. When you select a file in Finder and press Space, Gander draws a rich preview for developer files such as Markdown, Mermaid diagrams, JSON, SQLite databases and .env files. It also draws Finder thumbnails for most of them.

Which Macs does Gander run on?

Any Mac with macOS 15 or later.

Does Gander upload or collect my files?

No. Gander has no networking code and collects no data. Previews are drawn on your Mac, and the App Store privacy label is Data Not Collected.

Does previewing an SQLite database change it?

No. Gander opens databases read-only and immutable, so it never writes to the file or creates -wal, -shm or journal files beside it. Rows that exist only in an uncommitted -wal file aren’t shown, and the preview says so.

Will Gander show the secrets in my .env files?

Only when you ask. Every value is hidden when the preview opens; keys stay visible, and likely secrets are marked SECRET. Choose Show values to reveal them. Finder thumbnails of .env files show keys only.

Can Gander draw Mermaid diagrams inside Markdown?

Yes. A fenced code block marked mermaid is drawn as a diagram inside the rendered page, and .mmd or .mermaid files open as diagrams on their own.

I pressed Space and still see the standard preview. What now?

Open Gander once, then go to System Settings › General › Login Items & Extensions › Quick Look and make sure Gander is turned on. If another app previews the same file type, turn that one off. Then select the file in Finder and press Space again.

Why don’t SQLite files get a Gander thumbnail?

macOS doesn’t let third-party thumbnail extensions handle SQLite files, so Finder keeps its own icon. Pressing Space still opens the full Gander preview.

Can I turn some previews off?

Yes. The Gander window has a switch for each file category and for each Markdown extra: math, footnotes, GitHub alerts and emoji. Switch a category off and Gander stops handling that type.

Why do images in my Markdown show as text?

Quick Look previews can’t load images, so Gander shows each image as a picture icon and its alt text.