gRPC for .NET
Introduction
gRPC is "a modern open source high performance RPC framework that can run in any environment. It can efficiently connect services in and across data centers with pluggable support for load balancing, tracing, health checking and authentication. It is also applicable in last mile of distributed computing to connect devices, mobile applications and browsers to backend services."
grpc-dotnet
has been made available in .NET 3.0 (announced during .NET Conf 2019, on September the 23rd of 2019, .NET Core ❤ gRPC)
Source code is available on GitHub.
Learn
Look at the documentation on docs.microsoft.com and gRPC vs HTTP APIs.
Tutorials
Start with the tutorial from docs.microsoft.com.
There is an easy to read article from Laurent Kempé.