How to disable gatekeeper on macOS SONOMA?

If Darktable is not an officially identified app macOS will block you from installing it. At your own risk you can bypass the block.

Open a Mac app from an unidentified developer - Apple Support

Also from Darktable’s Mac support document...

Fixing issues with macOS security settings

Depending on the version of macOS, there maybe some warnings causing darktable not to run.

Dialog: “darktable” can’t be opened because it was not downloaded from the Mac App Store

Do one of the follow:

1. Locate darktable in Applications folder (or wherever you installed it) using Finder
2. Do “Open” via context menu
3. You will be presented with similar-looking dialog, but this time there will be second button allowing you to run the application
4. After that you will be able to start darktable without this trick (well, until you update it, then you will have to do above steps again)

Of course this depends on how certain you are that Marketable is a legit app. Quite frankly any developer who does not take the time to conform to Apple’s security requirements is a developer I would not buy anything from. It doesn’t take that much effort to do so.

From what I've found, Darktable has been around for quite a while and is a trusted app. Much like GIMP is an open source alternative to Photoshop, Darktable is an open source alternative to Lightroom.

If Sonoma is complaining that the app can't be confirmed as safe, then as lkrupp noted, you don't need to turn Gatekeeper off. Just right click on the app and choose Open. Confirm you want to do that and the OS will from then forward run the app without any messages.

It is a slightly odd that the app still doesn't have a code-signed version. Then again, if you don't have to pay the Apple developer fee in order to code-sign your app, why do it?

But that will eventually have to change. To give developers plenty of time, Apple has been slowly walking macOS to iOS' locked down and secured system. The System folder is already off limits, but another step I read a while back is that eventually, an app must be code-signed, or it will not run. Period. There was no timeline given for that change, but it is supposedly coming.

lkrupp wrote:

Of course this depends on how certain you are that Marketable is a legit app. Quite frankly any developer who does not take the time to conform to Apple’s security requirements is a developer I would not buy anything from. It doesn’t take that much effort to do so.

As fas as I can tell, you don't buy darktable. It's free to download, has no "in-app purchases," and the developers don't seem to be asking for donations of money.

It would be nice if they "signed" their builds, although I wouldn't hold my breath waiting for it.

Inadvisable. Why would you do that?

Did you read the install instructions for macOS? There is no mention of needing to disable Gatekeeper.

https://www.darktable.org/install/