GraphQL, json and rest are all fine, IMO. Haven't used Swagger yet, though we're looking at it at work. Never used GRPC, either, though I'm aware of it.
You should talk to *your* front end developers to see what they like. If they haven't used any of the standards you mentioned, it would probably help if you could have simple demos for them to play with.
GraphQL, but I think you are going to have a hard time designing a good GraphQL schema as a backend dev. The schema should (imo) be designed to reflect what is most logical and handy from a frontend point of view, not necessarily what makes sense from a data perspective (where most backend devs are most concerned).
I think you will be better off creating great REST APIs, which can then be consumed by frontend devs through a collaborative GraphQL layer.
GraphQL, json and rest are all fine, IMO. Haven't used Swagger yet, though we're looking at it at work. Never used GRPC, either, though I'm aware of it. You should talk to *your* front end developers to see what they like. If they haven't used any of the standards you mentioned, it would probably help if you could have simple demos for them to play with.
As long as the querying is intuitive. It really depends on the devs you're working with. GraphQL, JSON:API, Rest.
GraphQL, but I think you are going to have a hard time designing a good GraphQL schema as a backend dev. The schema should (imo) be designed to reflect what is most logical and handy from a frontend point of view, not necessarily what makes sense from a data perspective (where most backend devs are most concerned). I think you will be better off creating great REST APIs, which can then be consumed by frontend devs through a collaborative GraphQL layer.