all sites below have a clear way to search for only CC0 assets (what is CC0?):
general
Wikimedia Commons - search option (License: No restrictions)
itch.io - game assets. you have to search for CC0 specifically. everything here isn't CC0!
opengameart.org - game assets. you have to search for CC0 specifically. everything here isn't CC0!
images
Lexica - "All images on Lexica that were created with the Stable Diffusion 1.5 model are CC0 licensed", according to themselves (you have to manually search for Stable Diffusion 1.5 images specifically). This is what they said in January 2023, I hope nothing has changed around licenses since then (AI is a very fast-moving field).
flickr - you have to search for CC0 specifically. everything here isn't CC0!
openclipart.org - "an online media collection of more than 160 000 vectorial graphics, entirely in the public domain", according to themselves
freesvg.org - "download and upload SVG images with CC0 public domain license", according to themselves
stocksnap.io - "every single image on StockSnap are governed exclusively by the generous terms of the Creative Commons CC0 license", according to themselves
audio
freesound.org - you have to search for CC0 specifically. everything here isn't CC0!
Free Music Archive - you have to search for CC0 specifically. everything here isn't CC0!
video
vimeo - you have to search for CC0 specifically. everything here isn't CC0!
fonts
fontlibrary.org - you have to search for CC0 specifically. everything here isn't CC0!
publicdomainfiles.com - name is self-explanatory
3D models
BLEND SWAP - you have to search for CC0 specifically. everything here isn't CC0!
There are some public domain stuff on this page too. CC0 has some similarities to the public domain but isn't the exact same thing.
last updated 2023-12-25
last checked for accuracy 2023-05-14