Classical recordings and scores, most of them marked public domain, some not. Every recording carries its own licence icon, and on the one work page checked, one of six recordings was CC BY-NC-SA 3.0, which rules it out for a commercial game. Stays needs-review as a whole: this is an aggregator where the licence is decided per recording.
At a glance
Licence
varies
Commercial use
per-file review
Credit
Unclear: read the Notes
Status
needs-review: Useful, but a real question is open. Verify before you ship.
Check the licence icon on the exact recording you download. On Chopin's Nocturnes, Op. 9, five recordings link the Public Domain Mark 1.0 and one (Op. 9 no. 3, Gleb Ivanov) links CC BY-NC-SA 3.0. The same piece can be safe from one performer and non-commercial from another
The Public Domain Mark is a label, not a licence: it records Musopen's view that the recording is free of copyright. The Terms of Use say Musopen "does not warrant that all content is in the public domain" and that users "are responsible for determining the copyright status"
The composition being public domain does not settle the recording. Interactive use needs the recording's own status
The site Terms of Use also contain a generic "personal, non-commercial transitory viewing" clause for "materials (information or software)" on the website. It sits alongside per-recording licence icons and reads as boilerplate for the site itself, but it is on the page; this catalog does not resolve that conflict for you
Musopen's licence URLs (/license/, /about/license/) return 404; the Terms of Use page (/tos/) and the per-recording icons are where the statements live. The site is behind Cloudflare and loads only in a browser
Evidence
Live musopen.org/music/ (2026-09-23): "All the music we host is royalty and copyright free. For specific restrictions when applicable, check the license icons."
Live musopen.org/music/108-nocturnes-op-9/ (2026-09-23): per-recording links to creativecommons.org/publicdomain/mark/1.0/ (five recordings) and creativecommons.org/licenses/by-nc-sa/3.0/ (Op. 9 no. 3, Gleb Ivanov)
Live musopen.org/tos/ (2026-09-23): "Musopen provides access to music and sheet music that is believed to be in the public domain. However, Musopen does not warrant that all content is in the public domain"