Twitter made a change to its Twitter API last week that broke popular Twitter apps like Twitterrific and Tweetbot. In what is the last episode of the company’s troubled relationship with developers, Twitter has quietly updated its Developer Agreement to explicitly say that building apps that replicate official Twitter applications is no longer allowed (via Engadget).

According to the new rules, developers can no longer “use or access the Licensed Materials to create or attempt to create a substitute or similar service or product to the Twitter Applications.” As a result, the ecosystem of third-party clients that really helped Twitter become a social media juggernaut is now being obliterated.

This is obviously devastating news for small developers. Sean Heber, one of the developers of Twitterrific announced yesterday that the Twitterrific apps for iOS and macOS have now been removed from both App Stores. If subscriptions will be automatically canceled, Heber gently asked users not to request a refund from Apple.

“The loss of ongoing, recurring revenue from Twitterrific is already going to hurt our business significantly, and any refunds will come directly out of our pockets – not Twitter’s and not Apple’s. To put it simply, thousands of refunds would be devastating to a small company like ours,” Heber emphasized.

As Twitter recently tweaked its apps to put an algorithmic feed front and center, the demise of third-party clients is certainly going to be quite painful for power users. On the desktop, the Twitter-owned TweetDeck remains a decent alternative to Twitter.com, though it’s still missing some features that Twitter implemented in its official apps.

In the short term, it may be in Twitter’s best interest to bring all users to its official apps, so they can see more ads and maybe subscribe to Twitter Blue to get a better experience. Twitter Blue rolled out the Twitter Android app earlier this week, and the company also introduced a slightly cheaper annual plan for Twitter Blue ($84/year) if you subscribe to it on the web.