Offline SFD Diagram Generator API

I'm looking for a skilled developer to create a standalone, offline graphic generation API that replicates the functionality of the Excreta-Flow Diagram (SFD) Generator. This tool is essential for waste management decision-making and must be robust and user-friendly.

Key Requirements:
- Platform: Windows
- Input Data: Users can provide data via JSON files and manual data entry.
- Integrated Dashboard:
- Data visualization tools
- Interactive diagram editing

Ideal Skills & Experience:
- Strong expertise in API development
- Experience with data visualization
- Proficient in creating user-friendly dashboards
- Familiarity with waste management concepts is a plus

The solution should be self-contained, requiring no internet connection for operation.