useGolang (usegolang.com) is the paid course platform of Jon Calhoun, a US developer and one of the longest-running independent Go educators on the open web. He has been publishing Go tutorials and books continuously since the language's early years and is widely cited for the depth of his web-development-with-Go material.
His CourseFlix listing carries three useGolang courses: Web Development with Go v2 (Current Version), the original Learn to Create Web Applications using Go, and Testing with Go. The web-development course is the canonical paid resource for building production web applications with Go's standard library and the lightweight ecosystem around it.
Material is paid and aimed at Go developers building real web applications without depending on heavy frameworks. For broader Go content, see CourseFlix's Golang category page.