Grayjay Desktop App

The App Store forbids any app that violates the terms of service of any company [1], regardless of the legality [2]. Since YouTube forbids alternative clients in their terms of service, Apple will not allow Grayjay onto the App Store. Even in the EU, where multiple app stores are available, you still need to follow a subset of the App Store guidelines. I looked through them and it appears that the ToS violation guideline is in fact exempt for EU apps [1], so they could release a version in the EU exclusively. However, they may be subject to the Core Technology Fee.

[1] 5.2.2, 5.2.3: https://developer.apple.com/app-store/review/guidelines/#int...

[2] https://www.eff.org/deeplinks/2020/04/federal-judge-rules-it...

There is some precedent for Apple allowing apps that can be used for ToS or even copyright infringement, as long as they have a plausible legal purpose and all the infringement happens through third-party plugins that are not advertised in the app. The example I'm most familiar with is Paperback. There's also precedent for Apple not caring about Google's terms in particular, e.g. with Musi, though I guess that did get taken down in the end.

Grayjay also uses a plugin model, possibly for this exact reason. On the other hand, the infringing plugins are first-party and advertised via their website, so I somewhat doubt that either Google or Apple would allow it on their stores.