VSCO 2 Community Edition
Orchestral recordings by Versilian Studios (Sam Gossner). Released under the Creative Commons Zero (CC0 1.0) public-domain dedication: "no rules, no royalties, no limits on how or when you can use it."
Used for: strings (violin, viola and cello sections, solo double bass, harp), piccolo, flute, oboe, clarinet, bassoon, trumpet (open and muted), French horn (open and muted), tenor and bass trombone, tuba, timpani, snare drum, bass drum, cymbals, triangle, tam-tam, tambourine, xylophone, glockenspiel, marimba and upright piano. One take per note was chosen and compressed to MP3 for fast loading on the web.
Source: versilian-studios.com/vsco-community · github.com/sgossner/VSCO-2-CE
Sounds made in the browser
The celesta and chimes, and the effects that imitate techniques like col legno, sul ponticello, harmonics, flutter-tongue and con sordino on some instruments, are created by this website's own sound engine. English horn, bass clarinet and contrabassoon currently borrow the oboe, clarinet and bassoon recordings, lowered and darkened, until free recordings of those instruments are added.
Philharmonia Orchestra sound samples
Free to use inside your own music, but their terms say the samples "must not be sold or made available 'as is' (i.e. as samples or as a sampler instrument)". A web instrument like this studio counts as a sampler instrument, so they are not included unless permission is given.
Sonatina Symphonic Orchestra
Released under the Creative Commons Sampling Plus 1.0 license, which only allows sharing the samples themselves non-commercially. Because this site sells creative work and subscriptions, they are not included.
What you make is yours
Scores you write and export (WAV, stems, MIDI, MusicXML) belong to you. Because the recordings are public domain, you can use your exported music in films, videos and commercial projects without crediting anyone, though credit to Versilian Studios is always appreciated.