BookWidgets - BookWidgets is an excellent application that let you create engaging exercises in minutes and easily share a varied variety of beautiful and fun activities with your classroom and others.
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
Padlet - Visual boards for organizing anything.
draw.io - Online diagramming application
Socrative - Socrative helps teachers engage the class with educational activities to measure and visualize...
Visio - Simplify and communicate complex information using data-linked diagrams.