# Zip Estate

> AI-powered real estate investment platform with free public financial calculators and a computation API designed for both human users and AI agents. No authentication required for any public tool.

## IMPORTANT: This is a Client-Side Rendered SPA

zip-estate.com is built as a single-page application (React). Standard page routes (e.g. /calculators/real-estate) return a JavaScript bundle that web scrapers and AI fetchers cannot read directly. **Use the server-rendered API endpoints below** — they return raw JSON/Markdown and do NOT require JavaScript rendering.

## Server-Rendered Endpoints (No JS Required)

| Endpoint | Method | Content-Type | Purpose |
|----------|--------|-------------|----------|
| https://zip-estate.com/functions/llmsTxt | GET | text/markdown | This file — full AI agent instructions |
| https://zip-estate.com/functions/agentManifest | GET | application/json | Structured discovery manifest |
| https://zip-estate.com/functions/openApiJson | GET | application/json | Standard OpenAPI 3.1 specification |
| https://zip-estate.com/functions/calculatorApi | POST | application/json | Stateless computation API |

**Browser-friendly page:** https://zip-estate.com/agent-context — HTML version with copy button (requires JS rendering).

## Calculator API — Quick Start

All actions are POST requests with JSON body. No API key needed.

### List all calculators
```json
POST https://zip-estate.com/functions/calculatorApi
{ "action": "list" }
```

### Get full documentation for a calculator
```json
POST https://zip-estate.com/functions/calculatorApi
{ "action": "skill", "calculator": "realestate" }
```

### Run a calculation
```json
POST https://zip-estate.com/functions/calculatorApi
{ "action": "compute", "calculator": "realestate", "inputs": { "purchasePrice": 85000, "monthlyRent": 1100, "belowMarketPercent": 30 } }
```
Omitted inputs use sensible defaults. Returns structured JSON results + Markdown report.

### Generate a shareable URL
```json
POST https://zip-estate.com/functions/calculatorApi
{ "action": "generate_url", "calculator": "realestate", "inputs": { "purchasePrice": 85000, "monthlyRent": 1100 } }
```

## Available Calculators

| ID | Name | URL | Description |
|----|------|-----|-------------|
| realestate | Real Estate Investment Calculator | https://zip-estate.com/calculators/real-estate | Analyze rental properties with 4 engines of profit: Cash Flow, Appreciation, Principal Paydown, Below-Market Equity. 30-year projections. |
| compound | Compound Interest Calculator | https://zip-estate.com/calculators/compound | Visualize compound interest growth with initial investment, monthly contributions, rate, and time period. |
| doubling | Doubling Calculator | https://zip-estate.com/calculators/doubling | Rule of 72 and exact logarithmic doubling time calculation. |
| flip | Flip Calculator | https://zip-estate.com/calculators/flip | Compare All Cash vs Hard Money Loan scenarios for house flips. |
| leverage | Leverage Power Calculator | https://zip-estate.com/calculators/leverage | Leveraged vs unleveraged investing comparison. |
| pension | Pension Planning Calculator | https://zip-estate.com/calculators/pension | Retirement savings planning. |
| tax | Tax Efficiency Calculator | https://zip-estate.com/calculators/tax | Compare investment accounts by tax treatment. |
| loan-vs-sell | Portfolio Loan vs Sell | https://zip-estate.com/calculators/loan-vs-sell | Borrow against or sell your portfolio? |
| carwise | CarWise Comparison | https://zip-estate.com/calculators/carwise | Total cost of car ownership comparison (interactive only, no API). |

## URL Parameters — Real Estate Calculator (`/calculators/real-estate`)

| Param | Description | Default |
|-------|-------------|---------|
| pp | Purchase price ($) | 100000 |
| bm | Below market (%) | 0 |
| mr | Monthly rent ($) | 1500 |
| ar | Appreciation rate (%) | 4 |
| rg | Rent growth rate (%) | 3 |
| dp | Down payment (%) | 25 |
| cc | Closing costs ($) | 8000 |
| vr | Vacancy rate (%) | 8 |
| it | Insurance+tax monthly ($) | 200 |
| pm | Property management (%) | 10 |
| mt | Maintenance (%) | 0.5 |
| mi | Mortgage rate (%) | 6.5 |
| my | Mortgage term (years) | 30 |

Example: [Open calculator](https://zip-estate.com/calculators/real-estate?pp=85000&mr=1100&bm=30&dp=25)

### Compound Interest Calculator (`/calculators/compound`)

| Param | Description | Default |
|-------|-------------|---------|  
| ii | Initial investment ($) | 10000 |
| mc | Monthly contribution ($) | 500 |
| ar | Annual rate (%) | 8 |
| yr | Years | 30 |

Example: [Open calculator](https://zip-estate.com/calculators/compound?ii=50000&mc=1000&ar=10&yr=20)

### Doubling Calculator (`/calculators/doubling`)

| Param | Description | Default |
|-------|-------------|---------|  
| r | Annual return rate (%) | 8 |

Example: [Open calculator](https://zip-estate.com/calculators/doubling?r=12)

### Flip Calculator (`/calculators/flip`)

| Param | Description | Default |
|-------|-------------|---------|  
| ap | Asking price ($) | 115000 |
| pp | Purchase price ($) | 105000 |
| ccf | Closing costs fixed ($) | 1500 |
| ccp | Closing costs (%) | 0 |
| rc | Rehab cost ($) | 25000 |
| sc | Staging cost ($) | 0 |
| cg | Contingency (%) | 10 |
| pm | Project months | 9 |
| hc | Holding cost monthly ($) | 375 |
| mr | Monthly rent ($) | 0 |
| arv | Estimated ARV ($) | 165000 |
| scp | Sale closing (%) | 8 |
| lp | Loan-to-cost (%) | 65 |
| lr | Loan interest (%) | 13 |
| lpt | Loan points (%) | 2 |
| lof | Origination fee ($) | 0 |
| ips | Investor profit share (%) | 50 |

Example: [Open calculator](https://zip-estate.com/calculators/flip?pp=80000&rc=30000&arv=150000)

### Leverage Power Calculator (`/calculators/leverage`)

| Param | Description | Default |
|-------|-------------|---------|  
| la | Loan amount ($) | 100000 |
| lt | Loan term (years) | 10 |
| lr | Loan rate (%) | 8 |
| ir | Investment rate (%) | 8 |
| inf | Inflation rate (%) | 3 |
| gm | Grace months | 12 |

Example: [Open calculator](https://zip-estate.com/calculators/leverage?la=200000&lt=15&ir=10)

### Pension Planning Calculator (`/calculators/pension`)

| Param | Description | Default |
|-------|-------------|---------|  
| ca | Current age | 30 |
| ra | Retirement age | 67 |
| le | Life expectancy | 90 |
| cs | Current savings ($) | 50000 |
| ms | Monthly savings ($) | 1500 |
| ar | Annual return (%) | 7 |
| inf | Inflation (%) | 2.5 |
| di | Desired income ($) | 5000 |
| ss | Social security ($) | 1500 |

Example: [Open calculator](https://zip-estate.com/calculators/pension?ca=35&ms=2000&di=6000)

### Tax Efficiency Calculator (`/calculators/tax`)

| Param | Description | Default |
|-------|-------------|---------|  
| ii | Initial investment ($) | 50000 |
| ar | Annual return (%) | 8 |
| yr | Years | 30 |
| itr | Income tax rate (%) | 30 |
| cg | Capital gains tax (%) | 25 |
| dy | Dividend yield (%) | 2 |
| ac | Annual contribution ($) | 6000 |

Example: [Open calculator](https://zip-estate.com/calculators/tax?ii=100000&ar=10&yr=25)

### Portfolio Loan vs Sell Calculator (`/calculators/loan-vs-sell`)

| Param | Description | Default |
|-------|-------------|---------|  
| pv | Portfolio value ($) | 500000 |
| an | Amount needed ($) | 100000 |
| cb | Cost basis ($) | 200000 |
| er | Expected return (%) | 8 |
| lr | Loan interest rate (%) | 5.5 |
| lt | Loan term (years) | 5 |
| cg | Capital gains tax (%) | 25 |

Example: [Open calculator](https://zip-estate.com/calculators/loan-vs-sell?pv=1000000&an=200000)

## How to Use in Agent Responses

1. Call the Calculator API with `action: "compute"` to get structured results.
2. Call `action: "generate_url"` with the same inputs to get a shareable link.
3. **IMPORTANT: Always present links as clickable Markdown links, NOT raw URLs.**
   - ✅ Good: `[Open in Real Estate Calculator](https://zip-estate.com/calculators/real-estate?pp=85000&mr=1100)`
   - ❌ Bad: `https://zip-estate.com/calculators/real-estate?pp=85000&mr=1100`
   - Use a descriptive label like "Open in Calculator", "Try it yourself", or "See full analysis"
4. All public tools work without authentication or API keys.

## Information Pages

- [Home](https://zip-estate.com/): Landing page — company overview, investment thesis, team.
- [How We Make Money](https://zip-estate.com/HowWeMakeMoney): Business model transparency page.
- [Contact Us](https://zip-estate.com/ContactUs): Contact form and information.
- [Privacy Policy](https://zip-estate.com/PrivacyPolicy)
- [Terms of Service](https://zip-estate.com/TermsOfService)

## Contact

- Email: info@zip-estate.com
- Website: https://zip-estate.com