BillMilli Construction Platform Development

What is BillMilli?
BillMilli is a construction project management platform that prevents costly mistakes and scope drift in homebuilding.
The Core Idea
• Every project requires a 3D building model (IFC/GLB file)
• Field teams capture photos that are linked to specific locations in the model
• The system detects when reality doesn’t match the model
• Owners approve or reject changes through a formal Variation Order process
• Construction progresses through 16 stages, with “freeze points” that prevent late-stage expensive changes
Who Uses It?
• Owners/Investors: Monitor projects, approve changes, control payments
• Contractors: Submit evidence, request approvals, manage field work
• Supervisors: Verify work quality, check compliance
Technology Stack
Backend
• Language: Python 3.11+
• Web Framework: FastAPI (REST API)
• Database: PostgreSQL
• ORM: SQLAlchemy 2.0
• File Storage: MinIO (S3-compatible)
• Migrations: Alembic
• 3D Processing: ifcopenshell (IFC files), ezdxf (DWG files), trimesh (geometry)
Frontend (Web Dashboard)
• Language: TypeScript
• Framework: React 18
• Build Tool: Vite
• State Management: TanStack Query (React Query)
• Routing: React Router
• 3D Viewer: Three.js with @react-three/fiber
• HTTP Client: Axios
• Validation: Zod
Mobile (Field App)
• Language: TypeScript
• Framework: React Native with Expo
• State Management: Redux Toolkit
• Camera/AR: Expo Camera with device sensors
• Navigation: React Navigation
Infrastructure
• Containerization: Docker + Docker Compose
• CI/CD: GitHub Actions
• Authentication: JWT tokens