Freesound
An open audio platform with tags, spectral previews, similarity search, an API, and downloads under Creative Commons licenses.
Why use it
It rapidly builds temporary SFX libraries, finds rare recordings, and can support internal search and annotation through the API.
Where it fits
Use art, animation, audio, levels, and narrative to make the game easy to read and its world convincing.
What to check
Each sound may use CC0, CC BY, or noncommercial terms, and recordings can involve privacy or trademarks; review every item individually.