O2 Litmus is a developer network that aims to make it easy for developers to create and launch mobile applications. It provides developers with free access to APIs, generous revenue sharing of 70% for developers, and a streamlined process for testing, launching, and monetizing apps. Since its launch, O2 Litmus has expanded to support additional devices, introduced premium testing options, and partnered with more companies. It plans to continue improving the platform and expanding its reach within the O2 and Telefonica groups.