Twitter, previously, was the best of both worlds. A first-party app “most” people used, and then a vibrant third party app ecosystem that others, mainly power users, loved.

Threads is this now. API is almost finished / ready for release.

You and I have very different definitions of "now" :)

In the early days, Twitter used to have a very open and friendly API. It's a big part of why users and third-party devs (I was both) loved it. Same thing was true of Facebook and Reddit.

Over time, they shut down their APIs (or charged huge fees) in an effort to intentionally kill off third-party clients and services.

A key goal for Bluesky is to "lock open" the network and the API so that it's impossible to reverse the decision.

Open source clients and algorithms could serve as a foundation for more end-user friendly abstractions and UIs, that let average users very plainly express (or not express) what they want to see, and who they want to be seen by.

Imagine a sort of plug in ecosystem with sane defaults

Could this worsen polarization by facilitating extremist fever swamps?

It's a consumer product and it has to compete as one. We've been pretty aware of that from the start.

I think you're under-estimating what's happening with 3rd-party feeds. That's a core pattern where independent services can integrate into the UX as if they're native to the product. This means turning the client into an open platform for third-party applications.

That's been a success with feeds. They're actively adopted and created by users. Most of the feeds are hosted by skyfeed, a 3P app which gives users a GUI to create them. The author of skyfeed submitted this actually. Talented dev afaict but I've not met them, which is kind of the point. (Looking forward to it though, redsolver!)

3P integration operates by a thick client model. We exchange typed JSON that describes content and interfaces. This lets services drive the client through request/response flows. We can bounce out to webviews when we need, but not executing code means better integration into the app, which means users get access to new experiences within the client and providers get users more easily. This being social protocol means that auth and high level verbs (following, liking, commenting) also come along. The Web 1.0 did quite a bit without client scripting, and I suspect this client can too.

I also want to mention: the product experience right now is establishing a UX on a protocol-driven network that feels good to consumers. Our metric for success wasn't whether it was novel; it was whether we could meet consumer expectations. If we can prove out scaling -- which I'm now confident we will -- then we've established the core of the network. After that we use that core as a backbone for 3P devs to build integrated experiences, and it should lead to a notably diverse product, and I think that's the compelling position for us to offer.