Every once in a while you need a texture, sound, or model for a game or a prototype. It's easy to get something on google, but then the licensing isn't always right, and you might not have money to buy from an asset store. For me this is where CC0 and copyright free sites are the perfect solution.
Here is my personal list of the my favorite free asset sites around, from textures to sky boxes and more! I have no affiliation with these site, this is just my personal list of resources for when budgets and time get too tight, and I figure it would be more useful online than on my hard drive!
Updated Dec 1st 2019
A spin-off of HDRI Haven, Texture Haven boasts the same high quality and all their assets are CC0 for use in any way! They have many resolutions for each texture set and everything is PBR ready.
CC0 Textures (Never personally used)
A massive library of copyright free fully PBR textures available in multiple resolutions and file formats!
Technical not free, they will give you 15 free credits to get some good textures! The library is mixed quality, sometimes really high end, sometimes just unprocessed photos, but they have the biggest library I have fount online. Definitely a go to site when I can't find what I need on Texture Haven.
This is a collection of free assets from the guys that run ZBrush and Sculptris. Not PBR or game ready, but lots and lots of variety!
Open Game Art - Textures (Never personally used)
A completely game-oriented library of 2D assets, lots of PBR textures.
Skyboxes & HDRIs
This is my go-to site for lighting and backgrounds, the guy who shoots these is very dedicated and every single asset if free for use in any project. The images a extremely high quality, they come in a bunch of resolutions for rendering or games, and many come with back-plates to make sure your shots look perfect!
HDRI-Skies (Never personally used)
I don't use this site as much since HDRI haven came out, but these HDRIs are all good quality and free!
Brushes & Alphas
This is a collection of free assets from the guys that run ZBrush and Sculptris. There are some really good brushes in here!
My go-to site for inspirational photgraphy, desktops, and splash screens. All the photos are gourgous, and allt eh photos are 100% free for any use!
Open Game Art - Sounds & Music (Never personally used)
This is great library of game sound effects and music. Sound is really important in games, and this collection of SFX will go a long way in building immersion.
Game-Icons (Never personally used)
A really nice, massive collection of game-oriented icons, all provided copyright free! They do ask that you credit the creators though.
Icons 8 (Never personally used)
Icons8 has a massive collection of super polished free icons with a really nice consistent look. They would like you to credit them though (see Icons8 licenseing).
The Noun Project (Never personally used)
The Noun Project is another source of polished, well designed icons. Most of the icons are copyright free with a credit to the icon creator.
3D Model Haven (Soon to be launched)
Open Game Art - 3D Art (Never personally used)
Limited selection, but some of these models are really good quality.
Google has curated an amazing collection of completely free fonts. You can use them anywhere, and they are super optimized by design!
That's my list! I hope they serve you well when you need some quick, cheap and high quality resources!