1- https://github.com/dotnet/AspNetCore.Docs 2- https://github.com/aspnetboilerplate/aspnetboilerplate 3- https://github.com/bitwarden/server 4- https://github.com/abpframework/abp

ABP Framework provides a complete infrastructure for building modern web applications by following software development best practices and guidelines. With modern SaaS-enabled application templates, you can create your project in no time and start writing your business code right after creating your project. ABP runs on .NET 6 and is integrated with the latest versions of modern web components. Backed by a strong community with 8K stars on GitHub. I am sure that once you complete a project with ABP, you will not do "File > New Project" again!

https://aspnetzero.com/ - Application startup template for ASP.NET Core

It has tons of useful features that should be in a line of business application. It saves you more than 100 hours with pre-built pages (authentication, permission management, localization, multi-tenancy, SaaS features, CRUD Page Generator (RAD Tool), themes etc.)