Twitter has a prototype app called Twttr, Sarah Perez wrote for TechCrunch last month:
Twitter’s new prototype application is rolling out to the first group of testers starting today, the company announced this afternoon by way of a tweet. The app, which Twitter is calling “twttr” as a throwback to its original name, was first introduced at the CES conference this January. It aims to offer Twitter a more experimental testing space where the company can try out new ideas outside of its existing public network, gain feedback from testers, then develop new features as a result of what it learns.
Initially, the new twttr app will focus on testing new designs for conversations. As the company demonstrated at CES, the prototype app will show a different format for replies, where conversations themselves have a more rounded chat-like shape and are indented so they’re easier to follow. Engagements, sharing options and other tweet details are hidden from view in order to simplify reading through longer threads.
It’s not in the App Store (and it doesn’t sound like it will ever be), you fill out a form to request access.