Are you working on a game with the Unity game engine and want to use some 3rd party assets to make your game look better? Well, you do not have to spend all your savings to get you started. I compiled a list of websites where you can find game assets and tools that are absolutely free.
The Unity Asset Store is the obvious choice because it is the official marketplace curated by Unity itself. The majority of assets are paid, but you can still find more than 6000 completely free assets. Just use the search UI to only filter free assets. For example, here are free 3D models, free 2D assets like textures and characters, or free tools.
Due to the sheer number of Asset Store users, the most popular free assets usually have tens or even hundreds of reviews. That means that you can see if an asset is worth trying. Or, you can just try it yourself, because, you know, we are talking about free assets.
itch.io is a platform that primarily focuses on indie games and game jams. However, it also contains thousands of game dev related assets, some of which are also free. For example, here you find free game assets and here are free tools with the "Unity" tag.
When compared to the Unity Asset Store, the number of reviews is much lower. Also, because the marketplace is not curated, you should always make sure that you trust the author before downloading and running any executables.
One nice thing about itch.io is that you can often find assets with very permissive licenses. For example, this 2D tileset comes with a CC0 license, which means that I can use it for basically whatever I want.
Another great place for free game assets is the kenney.nl website where you can find thousands of different 3D models, 2D sprites and tiles and more. All the assets there are of great quality and usually under the CC0 license.
If you have done any programming before, you probably know github. You will probably not find too many graphics asset there, but you can still find some great tools. As a starter, you can use this repository search with the "Unity" keyword or explore this Unity topic.
I listed some popular places where you can find free Unity that should help you on your game dev journey. This list is far from exhaustive so feel free to explore any different options.