Volume Data Suite (VDS) is a free and open source app that can be used to visualize and interact with volumetric image data.
View the web demo app online at https://online.volumedatasuite.com or download the latest native version for your plattform.
The official documentation can be found at https://docs.volumedatasuite.com.
VDS is currently nothing more than a proof of concept and in a very early pre-alpha state. There are many features I want to add, and the API and User Interface is still evolving. Expect breaking changes!