Compatibility with Cloud.typography from Hoefler & Co, previously Hoefler & Frere-Jones.
Their homepage: Typography.com
If unfamiliar with the service:
They have been called "The Beatles of Type Design", with their fonts considered elegant and of the highest quality, and it is one of the most celebrated font studios in the Design world.
Their webfont service is not as widely known as (free) Google Fonts or (free / economic) Typekit, as they cater to a higher paying demographic with their own premium and more celebrated fonts.
Their product is, however, widely used by several Designers and well known companies. They host the web fonts themselves through their cloud.typography service to control illegal access to their product.
Their service requires access to their hosted fonts and does not require uploading fonts.