Twitter has updated its developer terms to officially ban the creation of third-party clients. The change was made in the "restrictions" section of the agreement, which now includes a clause prohibiting the "use or access the Licensed Materials to create or attempt to create a substitute or similar service or product to the Twitter Applications." This update comes a week after Twitter cut off access to several prominent third-party app developers.
The fact that Twitter did not communicate this to the developers, so they could make a smooth experience phasing out their app, is really just a slap in the face and a f*ck you. Which these developers really not deserve.
My favourite client was TweetBot. I also used Twitterrific for a time. Both made the Twitter experience a 100% better. Twitter's own app sucks.
“Since 2007, Twitterrific helped define the shape of the Twitter experience. It was the first desktop client, the first mobile client, one of the very first apps in the App Store, an Apple Design award winner, and it even helped redefine the word “tweet” in the dictionary. Ollie, Twitterrific’s bluebird mascot, was so popular it even prompted Twitter themselves to later adopt a bluebird logo of their very own. Our little app made a big dent on the world!”
Twitter client apps were used by designers and developers to demonstrate their abilities and push the boundaries of user experience and design for a long time. One example of this is the developer of Tweetie who created the "pull-to-refresh" mechanism, which is now a common feature in mobile apps.