Fermata is built on the work of others. Thank you to everyone below.
The player itself. © the Fermata authors; all rights reserved for now.
Music engraving, LGPL 3. It is shipped as a separate file, verovio-toolkit-wasm.js, which you can replace with your own build. verovio.org.
The piano samples, by Alexander Holm, CC BY 3.0. freepats.zenvoid.org.
The General MIDI sound bank, by S. Christian Collins, under its own license, which permits redistribution. github.com/mrbumpy409/GeneralUser-GS.
The sung voice is built from VocalSet by Julia Wilkins, Prem Seetharaman, Alison Wahl and Bryan Pardo, CC BY 4.0. Zenodo record 1442513.
The toolbar icons, MIT. phosphoricons.com.
The font for lyrics and names in the score, SIL Open Font License 1.1. github.com/liberationfonts/liberation-fonts.
The Ogg Opus codec, a Rust port of libopus, BSD-3-Clause. crates.io/crates/opus-rs.
The rest is Rust crates under their own permissive licenses (mostly MIT or Apache-2.0). The full list with versions is available on request.