WrittenUp is a website that allows remotely collaborating users to instantly write and draw on a virtual whiteboard, using their tablet or computer. It features multiple pages and PDF exporting.
IDroo Alternatives
IDroo is described as 'A shared whiteboard for use by multiple Skype-users simultaneously' and is a Whiteboard in the office & productivity category. There are more than 25 alternatives to IDroo for a variety of platforms, including Web-based, iPad, SaaS, Android and iPhone apps. The best IDroo alternative is Excalidraw, which is both free and Open Source. Other great apps like IDroo are Miro, OpenBoard Whiteboard, tldraw and Witeboard.