When my clients need professional and fast engineering 3D visualization on the browser, Zea is the best choice out there. They are quick to respond to issues and implement new capabilities. Most of their products are open source and you can submit issues direclty on github. All in all, the Zea team is great to work with. Review collected by and hosted on G2.com.

The docs could be more extensive but they have a great set of template/sample apps of github that show how you to implement various functionality as well as a forum that they respond to fairly quickly. Review collected by and hosted on G2.com.