A context diagram, also known as a system context diagram or level-0 Data Flow Diagram, shows a high-level overview of flow of data within a system, commonly used by Business Analysts. Its a non-technical design document.
It shows how your product interacts with outside organisations and systems.
The core element of a context diagram is a circle, or bubble, representing your system. Consider this system as a black box.
Next elements are real world entities which can be represented using rectangles or boxes. These entities communicates or exchanges data with your system.
Arrows represent the direction of data flow.
In real world context diagram mostly used by the project stakeholders.
Online tools to create good diagrams -
Gleek can be a good tool to create free diagram (developers friendly) :) -
Gleek | Diagram maker
Gleek is a text-to-diagram tool, it turns descriptions (in its own syntax) into diagrams. How Gleek works? Create…
You can use Edrawmax as well.
Creately can help as well.