Consider the following alternatives:
- built_value provides advanced features for building any Dart client for JSON-speaking APIs
- googleapis is a collection of pregenerated clients to various pubilc Google APIs.
- gRPC is a high-performance, open-source universal RPC framework (https://grpc.io/)
Streamy was a JSON RPC framework for applications written using Dart programming language. It generated a Dart client library from a Google API Discovery file.