How to build API-as-a-product projects?

Hey guys, there is one direction of software development that I want to talk about. It's API development. If you're building a B2B product in the form of APIs, you should know some specifics of developing such projects like what protocol to choose, and what practices to apply.

This is what this guide is about https://mobidev.biz/blog/api-development-integration-guide-rest-graphql-grpc

I really hope you'll find some insights there. Also, feel free to share your experience in building API-focused software. I'd love to hear it.