IDroo is an educational online whiteboard app that gives instant + real-time collaboration through your browser.
IDroo connects students and teachers all over the globbe.
The tool gives you a whiteboard which you can freely edit.
Make use of freehand, documents, formula & equation facilities as well in IDroo.
You can also upload images as well as other documents using a simple drag-drop to board or pasting.
Free version with 5 boards available. Standard at 9 EUR/user/mo (50 Boards), Premium at 25 Euro/user/mo (unlimited boards). Storage also increases in higher packages.