For iPad, there’s OmniGraffle[1]. Omni has been making software for Apple platforms and NeXTSTEP for several decades and is loved by many for its quality softwa

For iPad, there’s OmniGraffle[1]. Omni has been making software for Apple platforms and NeXTSTEP for several decades and is loved by many for its quality software and Apple-only approach. That’s not to say there isn’t a market for freehand diagramming software for iOS beyond OmniGraffle, but it has a big head-start (in maturity as well as mindshare). I don’t use an Android tablet, so I don’t know if anything similar is already offered on Google Play (Omni doesn’t make products for Android). If there wasn’t such a product yet, that would explain why Android users are enthusiastic about this product. [1] http://www.omnigroup.com/products/omnigraffle-ipad/ http://www.omnigroup.com/products/omnigraffle-ipad/