JSON:API is a specification for how a client should request that resources be fetched or modified, and how a server should respond to those requests.
JSON:API is designed to minimize both the number of requests and the amount of data transmitted between clients and servers. This efficiency is achieved without compromising readability, flexibility, or discoverability.
JSON:API requires use of the JSON:API media type (application/vnd.api+json) for exchanging data.
It seems like there have been many similar attempts at similar standards in the past, but hopefully this one sticks.