How to Use the Crypto Tax Calculator API — Free REST + MCP Server

#crypto #tax #api #mcp

Tax season with crypto is painful. Different cost basis methods give wildly different results — FIFO might save you thousands vs LIFO depending on market conditions. This API calculates capital gains and losses using all three methods so you can pick the optimal one.

Try It Right Now

curl -s https://api.lazy-mac.com/crypto-tax/api/v1/methods | jq

Response:

{
  "methods": [
    {
      "id": "fifo",
      "name": "First In First Out",
      "description": "Sells the oldest purchased coins first."
    },
    {
      "id": "lifo",
      "name": "Last In First Out",
      "description": "Sells the most recently purchased coins first."
    },
    {
      "id": "average",
      "name": "Average Cost",
      "description": "Uses the weighted average cost of all holdings."
    }
  ]
}

Calculate Capital Gains

curl -s -X POST https://api.lazy-mac.com/crypto-tax/api/v1/calculate \
  -H "Content-Type: application/json" \
  -d '{
    "method": "fifo",
    "transactions": [
      {"type": "buy", "amount": 1.0, "price": 30000, "date": "2025-01-15"},
      {"type": "buy", "amount": 0.5, "price": 45000, "date": "2025-06-01"},
      {"type": "sell", "amount": 0.8, "price": 50000, "date": "2025-12-01"}
    ]
  }' | jq

All Endpoints

Endpoint	Description
`POST /api/v1/calculate`	Calculate gains with specific method
`POST /api/v1/csv`	Upload CSV of transactions
`GET /api/v1/methods`	List supported accounting methods
`POST /api/v1/summary`	Annual summary report

Compare All Methods

Run the same transactions through FIFO, LIFO, and Average to find which saves you the most:

import requests

txns = [
    {"type": "buy", "amount": 1.0, "price": 30000, "date": "2025-01-15"},
    {"type": "sell", "amount": 0.5, "price": 55000, "date": "2025-11-01"}
]

for method in ["fifo", "lifo", "average"]:
    r = requests.post(
        "https://api.lazy-mac.com/crypto-tax/api/v1/calculate",
        json={"method": method, "transactions": txns}
    ).json()
    print(f"{method.upper()}: {r}")

Use as an MCP Server

{
  "mcpServers": {
    "crypto-tax": {
      "url": "https://api.lazy-mac.com/crypto-tax/mcp"
    }
  }
}

Ask Claude: "Calculate my capital gains for these trades using FIFO"

Pricing

Tier	Requests/mo	Price
Free	100	$0
Pro	10,000	$9/mo
Business	Unlimited	$49/mo

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