Why a New SDK?
The auth0.js library has been our default browser-based SDK for the last few years and has been a key part of our product and success. It has over 100K+ weekly downloads and is used by almost every Auth0 customer in one way or the other.
Over this time, we have developed a large set of capabilities in the core product. As the platform has moved forward, auth0.js has grown in size and capabilities. While auth0.js is an extremely powerful SDK that can handle a large number of different scenarios, this versatility comes at a price.
We went back to the drawing board and we re-imagined how a web platform SDK should work for the most common scenarios developers will be implementing.