A great review of Knots 3D from app review website dotTech:
Overall, I was very impressed with this app. There is a huge variety of knots here, and they are well-organized. The animated 3D diagrams make it really easy to see how a knot comes together, even if there are multiple strands involved.
As a history nerd, I particularly enjoyed the descriptions that come along with each knot. Having some background about how the knots were used and devised in centuries past is actually very helpful when you are trying to figure out what knot it best for a certain situation
Read the full review here: http://dottech.org/126483/ios-iphone-ipad-review-knots-3d-app/