Series 30+ (abbreviated as S30+) is a software platform and application user interface used for Nokia-branded mobile devices. The platform was introduced by Nokia in September 2013, first appearing on the Nokia 108, and has been the main Nokia feature phone operating system after the end of the Series 30 and Series 40 platforms in 2014. Despite the similar name and user interface, S30+ is technically completely different and unrelated to S30. Some newer phone models with "Series 30+" platform are said to be based on RTOS.