How to set default application for special link types (e.g., ssh://)?

Question

Some applications will signal to the OS that they can open special link type, such as ssh:// or github-mac://. They get automatically opened for such links by the web browser (or when using open in a terminal). If I have multiple such applications, how can I set which one should be the default?

For example, both GitHub Desktop and SourceTree can handle github-mac://. When I installed GitHub Desktop, it became the default handler for these links. How can I set SourceTree as the default handler without uninstalling GitHub Desktop?

Answer 1

Update December 2020
Rubicode (RCDefaultApp) seems to have gone. That leaves SwiftDefaultApps as the new go-to for this task.

Late Edit July 2019:
Though RCDefaultApp still works on Mojave, it may not survive Catalina [time will tell]
There is, however, a new kid on the block - SwiftDefaultApps, which may become the newer standard. Time will tell (again;)

Very late edit May 2020. I have no Mac that can run Catalina, so I'm reliant on others to keep this answer up to date.
From comments, SwiftDefaultApps reported as working in Catalina 10.15.5

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You can do that with a freeware app called RCDefaultApp. It's ancient, but still works on El Capitan.
Update April 2019 - still works on Mojave too.

You can define the default app for any URL scheme.

I don't have one for github, but this shows how you can set, for example, ftps specifically to any installed app that supports the protocol.

Answer 2

You can also try this: https://onflapp.wordpress.com/lincastor/. It allows you to register arbitrary url schemes such as chrome-devtools://

Answer 3

Since it hasn't been mentioned yet, there is also a great, modern app called Choosy that can be used to change default browser-opening behavior for different links, different times of day, etc.