Everything on this machine, in one place.
Add a key for as many as you like — each is remembered separately, so switching between them in the console never means pasting one twice. Every one of these has a free tier that does not ask for a card.
Keys live in this browser and are sent only to the provider they belong to. They are never uploaded, so they do not follow you to another machine — add them again there. Which provider you picked, and the model for each, do follow you if you sign in.
Optional. Talking to your own calculator never needs an account — this is for the parts that involve other people.
Everything in the console works without one.