Public Docker v2 API Endpoints
I just inspected the network request and found this. Maybe it'll help
https://hub.docker.com/v2/search/repositories/?query=alpineSo I think the answer to your question is just hub.docker.com/v2, but reading the API v2 Roadmap, it isn't too clear on what all the endpoints and their supported parameters are (the Docker Hub REST API seems to be undocumented, unlike the Docker Registry API).