EggNest

Monte Carlo retirement simulation with real tax calculations.

eggnest.co | app.eggnest.co

What is EggNest?

EggNest is a retirement planning simulator that runs thousands of Monte Carlo simulations to show you the probability distribution of outcomes—not just a single "expected" result. Unlike other calculators, EggNest uses PolicyEngine to calculate actual federal and state taxes, giving you accurate after-tax projections.

Features

• Monte Carlo Simulation: 10,000+ scenarios showing the range of possible outcomes
• Real Tax Calculations: Federal + state income tax via PolicyEngine-US (not estimates)
• Social Security Optimization: Model different claiming ages (62-70)
• Spouse Support: Joint simulation with mortality modeling
• Annuity Comparison: Compare guaranteed income vs. portfolio withdrawals
• What-If Scenarios: Quickly explore spending and savings changes

Architecture

eggnest/
├── app/                     # React frontend (app.eggnest.co)
│   └── src/
│       ├── components/      # Wizard, SimulationProgress
│       ├── pages/           # SimulatorPage
│       └── lib/api.ts       # API client with SSE streaming
├── web/                     # Landing page (eggnest.co)
│   └── src/pages/           # HomePage, ThesisPage
├── api/                     # Python FastAPI backend
│   └── eggnest/
│       ├── simulation.py    # MonteCarloSimulator (vectorized NumPy)
│       ├── tax.py           # PolicyEngine-US integration
│       └── models.py        # Pydantic models
└── supabase/                # Database migrations

Development

Backend (Python/FastAPI)

cd api
uv venv && uv pip install -e ".[dev]"
uv run uvicorn main:app --reload --port 8000

Frontend (React/Vite)

cd app
npm install
npm run dev  # Runs on port 5174

Landing Page

cd web
npm install
npm run dev  # Runs on port 5173

Stack

• Frontend: React 19 + Vite + TypeScript + Plotly
• Backend: Python + FastAPI + NumPy + PolicyEngine-US
• Database: Supabase (Postgres + Auth)
• Hosting: Vercel (frontend) + Modal (API)
• Tax Engine: PolicyEngine-US

License

MIT