UI Kit

We consolidate our component designs in one central place to enable effortless exploration and prototyping.

When we analyze the visual anatomy of today's most popular apps, we can observe a very high degree of consistency, making them feel polished, easy to navigate, and generally pleasant to interact with. Besides the consistent use of typography and color, we might find that the same paddings are applied to cards, forms, and menus, that the proportions of modules are affected similarly by viewport changes, and that animations all follow the same set of rules. To ensure the correct application of patterns and attributes defined by an underlying design language, digital product teams use standardized component libraries for their design work. Typically, these libraries contain modular building blocks, plus all relevant guidelines specifying nesting and recombination options. Increasingly, these libraries are referred to as UI Kits and are maintained in modern design tools such as Figma, Adobe XD, or Sketch.

The UI Kit in the context of Lean Design System

UI Kits are powerful tools and in the context of Lean Design System methodology, they play a vital role in cross-functional communication. They also enable effortless design exploration and prototyping. Before we take a look at an ideal design system stream, we internalize the following general guidelines on how to maintain an effective UI Kit:

  • Elements in our UI Kit should be structured and organized in a way that helps its users to apply the components correctly and effortlessly. Brad Frost's Atomic Design methodology outlines a reliable and battle-tested model for this and should, by now, almost be considered required reading for anyone working on digital products.

  • Our UI Kit should be kept clean and free of redundancies. Elements should be defined carefully and precisely, as every deficiency in our standard components will inevitably multiply over time and ripple into our project work. See also: Tidy up!

  • If possible, we should organize all our standard components in one shared file that should be considered the reference for all prototyping and exploration work. If we, for whatever reason, require a structure of multiple files, we should make sure repeating components are either linked directly or only defined in one of the files to avoid repetitive update work and potential discrepancies.

The consolidation of components in one central place makes it much easier to knock out consistent prototypes and represents a safe haven to return to from our visual explorations.

In case we decide to adopt Design Codification and establish a Steady Flow of Truth through our libraries, our code repository will provide the basis for all components in our UI Kit. In other words, we quite literally trace components exactly as they are rendered on devices and make them available as design components within our UI Kit. What may seem a bit cumbersome at first will ensure that the UI Kit never overtakes code repository. A component that can't be easily built using our technology should not be part of our UI Kit. This way, prototypes we design will always be close to the real thing and all testing we perform will be valid. The diagram below (fig. 1) illustrates where and how the UI Kit fits into our design system steam:

Next, we quickly go through the stations relevant to the UI Kit. For a complete description, see Steady Flow of Truth.

UI Kit

Very often, a UI Kit maintained in a modern design tool such as Figma, Adobe XD, or Sketch represents the first step for teams and organizations towards building a design system. The consolidation of components in one central place makes it much easier to knock out consistent prototypes and represents a safe haven to return to from our visual explorations. In the context of Lean Design System, prototypes are referred to as UX Vignettes, and the results of our explorations we call Tweaks. To make sure we all speak the same language, even across domains, element names and styles should be aligned with the naming conventions defined in our code repositories. See Fig. 2 below.

UX Vignettes

UX Vignettes are focused prototypes, covering a defined user scenario or workflow end-to-end. We build UX Vignettes using the components provided by our UI Kit. Ideally, UX Vignettes should be clickable and run on all targeted platforms. When determining our design tooling, prototyping capabilities should be a main criteria, as the process of building, testing and updating them should be quick and easy. If we want to make improvements or add new elements to our UI Kit's component library (because, for example, a project presents us with a new and unique challenge), we document them in separate tweaks files. These Tweaks files are shared design files in our design system stream.


We document all changes and additions to our UI Kit in separate Tweaks files, which are shared design files of the same type as the UI Kit itself. Tweaks can be the result of project work or regular optimization efforts. Whatever their origin, if we agree on their validity, we feed them into the code repository through the process of codification. Once codified, we can then make them available in our UI Kit by tracing them.

Where this tactic fits in

Diligently refactoring our design system artifacts will prevent our repositories from cluttering.

Tidy up!

Authors and contributors

D. Kurfess

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