Angular 8 + Spring Boot Microservices and Spring Cloud

A REST API exposes an application's data as resources at stable addresses and lets clients read and change them with HTTP's standard methods and status codes, so that the protocol itself carries most of the meaning.

JSON is a text format for exchanging structured data: values are strings, numbers, booleans or null, arranged in ordered arrays and in objects of name and value pairs, and every mainstream language reads and writes it without a library of its own.

GraphQL is a query language for APIs and a server-side runtime for answering those queries: a client asks for precisely the fields it needs from a typed schema, in one request, instead of calling several fixed endpoints and discarding most of what comes back.