Here is a list of downloads for compiled builds of the pixel art tool Aseprite.
Aseprite is an open source tool for drawing pixel art and animations with lots and lots of nice features.
You can find more info on the official website http://www.aseprite.org and the source code on the GitHub repository page.
If you want to compile the software yourself (under a GNU license) you can find a guide here.
The instructions works fine on Ubuntu, as I was able to compile right away with Ninja, on windows I had issues with it so I ended up using Visual Studio’s Nmake.
If you want an auto updating version, or if you want to support the devolopment of Aseprite you can purchase the tool on the official website. Please consider this option if it’s not a problem for you to spend a few dollars on an amazing tool.