Freesound is a collaborative repository of Creative Commons licensed audio samples, and non-profit organisation, with more than 500,000 sounds and effects (as of May 2021), and 8 million registered users (as of March 2019). Sounds are uploaded to the website by its users, and cover a wide range of subjects, from field recordings to synthesised sounds. Audio content in the repository can be tagged and browsed by folksonomic means as well as standard text-based search. Audio content in the repository is also analysed using the open-source audio analysis tool Essentia, which powers the similarity search functionality of the site.Freesound has a RESTful API through which third-party applications can access and retrieve audio content and its metadata.