I have been using a new open-source platform, API Logic Server (an open-source project on GitHub) to deliver API microservices for a client. I wanted to build a complete mobile banking API from start to finish based on the old TPC benchmark.  This includes declarative business logic (a.k.a. spreadsheet-like rules), security, react-admin UI, and an Open API (Swagger) documentation.

API Logic Server (ALS) creates executable projects that you can extend in your IDE.   It is an open-source Python platform based on SQLAlchemy 2.0, Flask, safrs-JSON API, react-admin, and LogicBank (a declarative spreadsheet-like rules engine).