The Qlik developer portal is the one place for you to find developer documentation, API references, tutorials, and much more for the Qlik Sense SaaS editions. The goal with the platform is to provide you, the developer, with all the necessary resources to be successful in leveraging the Qlik platform in programmatic ways.
The Basics section of the portal introduces you to the central concepts in the platform. It also goes through the various ways you can interact with the platform, how to build web solutions, client extensions, or embed the powerful analytics capabilities right into your existing solutions.
If you head over to the Tutorials section, you can access various tutorials, often on a relatively concrete use case level, that can accelerate your use of the platform, or perhaps teach you how to solve specific problems with the platform.
If you are experienced with the Qlik developer platform already, the APIs section contains all the down-to-the-method level documentation that you might need to consult when invoking certain endpoints or want to understand what a parameter does, or looks like.
If you're curious about the various software libraries and tools that can accelerate your use of the platform, head over to the Libraries & Tools section.
Finally, if you are ever in doubt, something that you don't quite understand, or information that you're simply missing, head over to the large Qlik community and discuss.