Today Google launched gRPC, a new HTTP/2 and Protocol Buffer based system for building APIs. This is Google's third system for web APIs. The first system was Google Data, which was based on the Atom Publishing Protocol [RFC 5023]. It was an XML protocol over HTTP. The serving system for that grew, but started to hit scalability issues at around 50 APIs. The scaling issues weren't in the realm of serving QPS, but more in the management of that many APIs, such as rolling out new features across all APIs and all clients.