Twitter is shutting down its experimental app twttr, which the company had used publicly to prototype new features back in 2019. The app was first introduced at the Consumer Electronics Show in January 2019, then launched to testers that March. Its primary focus had been on trying out new designs for threaded conversations, including things like how to branch replies, apply labels and color-code responses, among other things. Some of those tests eventually turned into Twitter features and the twttr app was no longer being used.

The idea to design in public was an interesting experiment by Twitter.

Most companies roll out internal beta tests, followed by smaller-scale A/B tests to a percentage of their public user base to get feedback about new ideas. But with twttr, the company actually invited its users to be a part of the much earlier-stage development process.

The concept for twttr had been spearheaded by Twitter’s then Director of Product Management, Sara Beykpour (then Sara Haider — she and Twitter Product Lead Kayvon Beykpour have since married). But Sara announced last year she would be stepping into a new role at the company and Twitter’s new product director in charge of conversations would be Suzanne Xie, who had joined by way of Twitter’s acquisition of Lightwell.

Work on twttr appeared to stop around the time Xie stepped in, as no other significant updates were released to twttr’s TestFlight user base. And Xie left Twitter this fall for Stripe.

Now, it seems that maintaining the largely unused app no longer makes sense for the company.

Twitter announced its plans to formally shut down twttr today, saying it was turning off the app in order to work on new tests related to the conversation taking place on Twitter itself. The shutdown appears to be immediate. Though the app may still function for those who have it installed, when the TestFlight build expires in 26 days, that may no longer be the case.

It’s not likely that twttr had many dedicated users at this point, especially as the app lacked Twitter’s newer features like Topics and Fleets, for example, and was no longer offering new experiments to test.

Twitter is not ruling out using twttr again at some point in the future, though. A spokesperson said the company is “exploring potential next steps for twttr,” as it develops its future plans to test new products.