A very good free whiteboard http://tldraw.com 
&& for devs too http://docs.tldraw.dev 

Documentation

Web Development

tldraw's headquarters in London, United Kingdom

This department focuses on the design, engineering, and enhancement of products.

This department focuses on optimizing sales processes and enhancing the overall efficiency of the sales function.

This department focuses on designing, coding, and testing software applications.

This department is responsible for creating and developing innovative product designs.

This department focuses on providing engineering support and expertise to various projects and initiatives.

This department focuses on innovative research and the development of new products and technologies.