What are some alternatives?
When comparing Making a product designer and Aproove, you can also consider the following products
Digital Behavioral Design - Human behavior is programmable. A book on product design.
Proof HQ - ProofHQ provides a medium for co-workers to annotate and collaborate before producing a clean, finished output.
Product Disrupt - A design student's list of resources to learn Product Design
ReviewStudio - ReviewStudio is an online proofing software built for easy collaboration on review and approval workflows, for all your image, video, web pages and PDF based projects.
Laws of UX - Key maxims that designers must consider when building UX
ProofHub - ProofHub is an online project management software that helps you to plan, collaborate, organize and deliver projects.