Don't waste your money
Purple is a documentation and project planning tool built for creative teams. Write documents, assign tasks, share images, and present your designs. With integrations like Google Docs, Sketch, Invision, and Airtable, all of your project work can be in one place - which makes it a breeze to share with your team or clients.
Cr4yon attempts to provide the same feel as real life whiteboard via a collaborative simple drawing interface.
You can draw and add text (HTML canvas) easily.
The product is at an early stage obviously but is very encouraging.