company. The service's API allows other web services and applications to integrate with Twitter. Developer interest in Twitter began immediately following its launch, prompting the company to release the first version of its public API in September 2006. The API quickly became iconic as a reference implementation for public REST APIs and is widely cited in programming tutorials. From 2006 until 2010, Twitter's developer platform experienced strong growth and a highly favorable reputation. Developers built upon the public API to create the first Twitter mobile phone clients as well as the first URL shortener. Between 2010 and 2012, however, Twitter made a number of decisions that were received unfavorably by the developer community. In 2010, Twitter mandated that all developers adopt OAuth authentication with just 9 weeks of notice. Later that year, Twitter launched its own URL shortener, in direct competition with some of its most well-known third-party developers. And in 2012, Twitter introduced stricter usage limits for its API, "completely crippling" some developers. While these moves successfully increased the stability and security of the service, they were broadly perceived as hostile to developers, causing them to lose trust in the platform. In July 2020, Twitter released version 2.0 of the public API and began showcasing Twitter apps made by third-party developers on its Twitter Toolbox section in April 2022. Innovators patent agreement On April 17, 2012, Twitter announced it would implement an "Innovators Patent Agreement" which would obligate Twitter to only use its patents . Open source Twitter has a history of both using and releasing open-source software while overcoming technical challenges of their service. A page in their developer documentation thanks dozens of open-source projects which they have used, from revision control software like Git to programming languages such as Ruby and Scala. Software released as open source by the company includes the Gizzard Scala framework for creating distributed datastores, the distributed graph database FlockDB, the Finagle library for building asynchronous RPC servers and clients, the TwUI user interface framework for iOS, and the Bower client-side package manager. The popular Bootstrap frontend framework was also started at Twitter and is 10th most popular repository on GitHub. Interface Twitter introduced the first major redesign of its user interface in September 2010, adopting a dual-pane layout with a navigation bar along the top of the screen, and an increased focus on the inline embedding of multimedia content. Critics considered the