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Developer API

Embed Astrilio calculators, access jurisdiction rules as JSON, or connect via our MCP server.

Embeddable Calculators

Embed any calculator on your website with a single iframe:

<iframe
  src="https://astrilio.com/embed/mortgage-payment"
  width="100%"
  height="600"
  frameborder="0"
  title="Mortgage Calculator by Astrilio"
></iframe>

Replace mortgage-payment with any of the 24 available calculator slugs.

Available Calculators

mortgage-paymentamortization-schedulerent-increasesecurity-depositprorated-rentaffordabilitycap-ratecash-flowland-transfer-taxcash-on-cashcmhc-pmidscrirrstr-revenuestr-vs-ltrdepreciationclosing-costrent-to-incomerental-price-estimatorrent-vs-buymoving-costgenerator-sizinginsulation-paybackheat-pump-vs-furnace

MCP Server

Astrilio exposes calculator tools via an MCP (Model Context Protocol) HTTP endpoint hosted in the Astrilio backend. AI agents — Claude, GPT-4, and any MCP-compatible host — can call Astrilio calculators server-side without embedding the math locally.

Endpoint

GET  https://api.astrilio.com/mcp/v1/tools         # list available tools
POST https://api.astrilio.com/mcp/v1/tools/call    # execute a tool

Example — list tools

curl https://api.astrilio.com/mcp/v1/tools

Example — call a tool

curl -X POST https://api.astrilio.com/mcp/v1/tools/call \
  -H "Content-Type: application/json" \
  -d '{
    "name": "mortgage_payment",
    "arguments": {
      "purchase_price": 750000,
      "down_payment": 150000,
      "annual_rate_pct": 5.5,
      "amort_years": 25
    }
  }'

Available Tools

mortgage_payment

Monthly mortgage payment with Canadian semi-annual or US monthly compounding.

{
  "purchase_price":  number,   // required — purchase price
  "down_payment":    number,   // required — down payment amount
  "annual_rate_pct": number,   // required — e.g. 5.5 for 5.5%
  "amort_years":     integer,  // required — 1–30
  "country":         string    // optional — "CA" (default) or "US"
}
cap_rate

Capitalization rate, NOI, and gross rent multiplier for a rental property.

{
  "purchase_price":   number,  // required
  "monthly_rent":     number,  // required — gross monthly rent
  "annual_expenses":  number,  // required — total operating expenses/yr
  "vacancy_rate_pct": number   // optional — default 5
}
cash_flow

Monthly and annual net cash flow after all operating expenses and mortgage.

{
  "monthly_rent":        number,  // required
  "monthly_mortgage":    number,  // required
  "annual_property_tax": number,  // required
  "annual_insurance":    number,  // required
  "annual_maintenance":  number,  // required
  "vacancy_rate_pct":    number,  // optional — default 5
  "monthly_pm_fee":      number   // optional — default 0
}
land_transfer_tax

Land transfer tax by Canadian province including Toronto municipal layer and first-time buyer rebates.

{
  "purchase_price":  number,   // required
  "province":        string,   // required — e.g. "ON", "BC", "AB"
  "include_toronto": boolean,  // optional — default false
  "first_time_buyer": boolean  // optional — default false
}
rent_increase_check

Check if a proposed rent increase is within the legal guideline for a Canadian province.

{
  "current_rent":  number,   // required
  "proposed_rent": number,   // required
  "province":      string,   // optional — default "ON"
  "year":          integer   // optional — default 2025
}
cmhc_premium

CMHC mortgage default insurance premium, rate tier, and monthly payment impact.

{
  "purchase_price": number,  // required — max $1,500,000
  "down_payment":   number   // required — min 5%
}

Response Format

// Success
{ "content": [{ "type": "text", "text": "Monthly payment: $3,204.12\n..." }] }

// Error
{ "content": [{ "type": "text", "text": "purchase_price must be > 0" }], "isError": true }

Rate Limits

Tool calls are limited to 20 requests per minute per IP. The tools list endpoint is unrestricted. A 429 Too Many Requests response is returned when the limit is exceeded.

More Developer Tools

Looking for broader developer utilities? Check out devtoolzy.com — a free collection of developer tools from Cosyslabs, including formatters, encoders, diff checkers, and more.

Open Rules API

All 64 jurisdiction packs are available as static JSON at /api/rules/<country>/<region>.json. Rules include rent increase guidelines, deposit limits, transfer tax brackets, and more — all with primary-source links and lastVerified timestamps. Free, no auth required.

index.jsonca/on.json (example)Full API docs