I found this tool when looking to learn more about WebVizio but I have to say that this tool is great and I'm really happy for taking this path.
Very clean and nice UX. Easy commenting and the annotation functionality is just great. The Slack integration is amazing too, as for my needs, being able to use the same channel per project, is perfect.
White labeling works perfectly and cname is a big advantage to keep things more professional.
I look forward to being able to comment on images and PDFs, public comments, and translations as I consider them essential. Ohh and Nifty integration!
Also, support has been amazing so far. Prompt reply and very friendly support.