Starting on Thursday night, Twitter cut off API access for some of the biggest third party clients.

From The Verge:

It’s hard to tell whether the third-party client outage is due to the API. Attempting certain calls from my individual Twitter developer account seemed to work, while Twitter’s own API explorer tool is currently broken.

It definitely seems like it is on purpose. For it to last this long without any update definitely makes it feel like it was done on purpose. Many developers' apps have started showing up as "suspended". In looking at my own account, I can see that both Tweetbot and Fenix are gone from my list of connected apps.

The Icon Factory (makers of Twitteriffic) have a blog post about it as well.

The complete silence from Twitter is completely baffling. Burning more than a decade of working with developers overnight seems incredibly stupid. As Paul Hadad, one of the makers of Tweetbot said:

Even during the darkest Twitter 1.0 days they were pretty open about what they were doing. I remember getting a call prior to the 4 quadrants token limit where they explained what was going to happen and answered questions. I wasn't happy but at least felt there was respect.