Surge XT is a free and open-source hybrid synthesizer, originally written and sold as a commercial product by @kurasu/Claes Johanson at Vember Audio. In September 2018, Claes decided to release a partially completed version of Surge 1.6 under GPL3, and a group of developers have been improving it since. You can learn more about the team at https://surge-synth-team.org/ or connect with us on Discord