It depends on your intent:
If you are a developer working on a licensed ASP.NET Zero project, here is your action plan regarding GitHub:
After purchase, email Volosoft support with your GitHub username. They will add you to Volosoft/aspnet-zero-core (private). asp.net zero github
No, ASP.NET Zero is not fully open source.
It is a commercial product sold by Volosoft. However, once you purchase a license, you get access to its private source code repository hosted on GitHub.
Short answer: No. Not for free.
Long answer: The source code is available on GitHub, but it is not open source.
This is the most confusing part for developers. You can search for "aspnetzero" on GitHub and find a repository. You can even git clone it. However, you will quickly hit a wall: You need a NuGet feed password and a license key to run the code. It depends on your intent: If you are
ASP.NET Zero is not open-source software. It is a proprietary Application Framework built on top of the open-source ASP.NET Boilerplate (ABP) Framework.
The company protects its intellectual property because ASP.NET Zero offers: If the code were on a public GitHub
If the code were on a public GitHub repository, anyone could bypass the license fee, violating the terms of use.