Writing APIs have been a big part of my career. I've written COM, DCOM, XML based APIs, ISAPI Filters, SOAP, REST, gRPC, and others. A lot of this time a new technology in writing APIs has been chasing the new ‘cool’ technology that would fix everything.
I started writing services in websites back in the .NET 1.0 days. Originally I was doing just POX (Plain Old XML) services in a very crude way so we could get the job done for our internal systems back in the early 2000's.