HumHub is an open source social network kit that's great for social intranets, enterprise social networks, and private social networks. It's self-hosted and has a powerful module system.
Loading Buttons are simple, animated buttons that show loading indicators that change to show whether the button action was successful or not.
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Calabash lets you write and execute automated acceptance tests of mobile apps. It supports both Android and iOS.
DPM is a package manager for Sketch plugins. It lets you simply keep plugins synced across teams and devices.
Slate makes it easy to create beautiful static documentation for your API. It has a clean, intuitive design and uses Markdown to format your text.
Voxel.css makes it easy to render 3D. It supports all image types and includes GPU acceleration and CSS3 transitions.
Whiteboard makes it easy to write beautiful API documentation. It's a NodeJS based project inspired by the Ruby-based Slate API documentation tool.
Timelined is a CSS-only vertical timeline that's fully customizable. You can use it to create static or dynamic timelines.