After years of warnings and several delays, Twitter finally made good today on its promise to kill off key features of popular streaming apps. In a blog post today, Twitter said it would remove access to APIs needed to power push notifications and an auto-refreshing timeline. Rob Johnson, a director of product, said Twitter would stop supporting those APIs so it could focus on its own native applications.

The changes affect popular third-party Twitter apps including Tweetbot, Twitterrific, Talon, and Tweetings. As Johnson wrote in a separate note to the company, third-party apps invented many features that were later adopted by the company in its native apps.

“Third-party clients have had a notable impact on the Twitter service and the products we build,” he wrote. “Independent developers built the first Twitter client for Mac and the first native app for iPhone. These clients pioneered product features we all know and love about Twitter, like mute, the pull-to-refresh gesture, and more.”

But Twitter warned developers against building clients that replicated the home timeline more than six years ago, saying it would focus future development on its native apps. Most newer Twitter features, including polls, bookmarks, and Periscopes, never made it to third-party apps, because Twitter would not include them in its APIs.

Twitter first announced the shutdown in April, with a target date of June 19th. In response to complaints from developers, it agreed to delay the shutdown so they would have more time to update their apps.

There’s a world in which Twitter embraced third-party developers fully, letting their energy and ideas infuse its struggling platform with new life. Most of Twitter’s best ideas have come not from the company, but from its users. But that would introduce new costs and complexity into a company that is struggling to meet basic business objectives.

Johnson’s full note to the company is below.