well at the moment if a font does not exist on your system, it goes through their cloud fonts endpoint. consider you are on a mac with no office suite installed

well at the moment if a font does not exist on your system, it goes through their cloud fonts endpoint. consider you are on a mac with no office suite installed and want to use "Blackadder ITC" it will call: GET https://fs.microsoft.com/fs/4.9/rawguids/35330309812 https://fs.microsoft.com/fs/4.9/rawguids/35330309812 which is basically the ttf file for blackadder itc. btw. there is also a list endpoint with all the "guids": https://fs.microsoft.com/fs/4.9/listAll.json https://fs.microsoft.com/fs/4.9/listAll.json (but it's encoded, so that you can't download all of them as easily)