prei — Passive Real Estate Investment Analytics

Welcome to the documentation for prei, a Django-based web application designed to analyze residential real estate investments for buy-and-hold investors.

What is prei?

prei computes key performance indicators (KPIs) such as:

• Cash-on-Cash Return — Annual pre-tax cash flow divided by total cash invested
• Capitalization Rate (Cap Rate) — Net Operating Income divided by property value
• Net Operating Income (NOI) — Total income minus operating expenses
• Internal Rate of Return (IRR) — Time-weighted return on investment
• Debt Service Coverage Ratio (DSCR) — NOI divided by annual debt service

Documentation Structure

This documentation follows the Diátaxis framework:

📚 Tutorials

Step-by-step lessons — start here if you're new.

🛠️ How-to Guides

Practical guides for local dev, Codespaces, Render deployment, and daily tasks.

📖 Reference

Financial KPIs, data sources, API keys — detailed technical info.

💡 Explanation

Architecture, design decisions, and the design system.

Quick Links

• Getting Started Tutorial
• Local Docker Setup
• Dev Container / Codespaces
• Deploy to Render
• API Keys Reference
• Financial KPIs
• GitHub Repository

Technology Stack

• Backend: Django 6.0 with Python 3.14
• Database: SQLite (dev), PostgreSQL (Render prod)
• Financial Libraries: NumPy, pandas
• Testing: pytest, pytest-django
• Code Quality: ruff, mypy

Repository

Source: https://github.com/paruff/prei