With a clean, minimal yet colourful style, the kit is Retina-ready and remixable; versatile enough to build all kinds of apps.
Its makers recommend you use it with InVision, making it easy for clients to work through your prototypes. Either way you can download the Do UI kit for free over on the InVision website, and it doesn't force you to share.
For more free UI kits, see this article.
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