LucidChart

Create plenty of diagrams, flow charts mind maps wireframes

Screenshots

View Image

Hunter's comment

Looking for a free and easy flowchart app? With Lucidchart's iPad application, you can create stunning flowcharts, wireframes, mockups, UML diagrams, ER diagrams, and much more!
Quote Source

Often students and even teachers need to draw different shapes and diagrams to eloborate a process. LucidChart is there to help them to deal with such situation. Make any shape, flowchart or wireframs easily.

Link

https://www.lucidchart.com/pages/ipad-flowchart-app