Congratulating the 2025 Spotify FOSS Fund Winners

Spotify has run the FOSS Fund since 2022 to support the open source ecosystem it depends on, and the 2025 fund was allocated to three projects.

• FFmpeg: €30,000
• Mock Service Worker (MSW): €15,000
• Xiph.Org Foundation: €25,000

FFmpeg is core media infrastructure developed almost entirely by volunteers. It has been actively developed for over 25 years and is widely used for decoding, encoding, transcoding, streaming, and playback. The maintainer explained that this funding will go toward hardware purchases, conference travel, and development projects, and emphasized that in the long term, more dedicated developer support and repeatable funding are needed.

MSW is a JavaScript library for API mocking used in Spotify's web stack and testing environments. Artem Zakharchenko, its founder and sole full-time maintainer, said he made major improvements in 2025, including the Interceptors architecture, node:net level network handling, and Server-Sent Events support, and that his goals for 2026 are to overhaul the internal architecture and complete remote request interception. Past funding was used mainly for living expenses, and he said he wants to compensate contributors in a more sustainable way going forward.

Xiph.Org Foundation has received funding every year since the Spotify FOSS Fund began. It maintains core audio formats and codecs such as Ogg, Opus, Vorbis, and FLAC, and has provided the foundation from Spotify's early audio delivery to its current music, podcast, and audiobook services. Beyond the technology itself, its documentation and educational materials are also widely used in Spotify's internal onboarding and across the broader audio ecosystem.

While the three projects differ in scale and structure, all of them stand on the work of countless open source contributors. This selection is significant as a direct way of giving back to the core infrastructure Spotify depends on.