What Problem Does This Solve?
Showcase all conceivable functions and data in one page.
Why Use This Pattern?
The Kitchen Sink approach, sometimes also referred to as Swiss Army Knife app or data portal, is useful for demo applications which showcase all (or almost all) of the features and is a great way to introduce users (e.g. developers) who are learning about a new platform/framework/library/API.
When to Use This Pattern
Use the Kitchen Sink approach when demoing the capabilities of a framework or library. The assumption here is that the user of the application is a person familiar with the environment, so she can walk the audience through a series of functions (the demo) or can access the function asked to showcase. Alternatively, the user can be a person that wants to learn more about a product or platform and is interesting in seeing and experimenting with all the functionality that is available.
Avoid Kitchen Sink for applications meant for the general audience because they violate common best practices for application design like Empty State, Onboarding, Task-Oriented, or Search & Edit. Validate requirements against true end-user needs and consider limiting functionality and progressively disclosing content and features or using single-topic maps.
What’s the Solution?
Provide an interface that allows users to access all the functionality through a series of buttons, tabs, and/or menus. Structuring the functions by API reference, by category or in another logical order is recommended.
The term Kitchen Sink is often used for applications that try to cram too much functionality and data into one interface and as a result appear busy, cluttered, and less appealing and user-friendly. As discussed before, providing an interface that anticipates and satisfies the task on hand is better than exposing a slew of functionality and data layers that is hard to understand and navigate.