Base URL
https://metalmetric.com/api/gpt?action={action}&{params}
All requests are GET. Responses are JSON. No authentication required. Rate limit: 30 requests/minute per IP.
Available Actions
Pass the action parameter to select a tool.
| Action | Method | Description |
|---|---|---|
| spot_prices | GET | Live gold, silver, platinum, palladium, copper prices |
| melt_value | GET | Melt value for 25 known coins or custom weight/purity |
| gold_silver_ratio | GET | Current GSR with zone signal and historical context |
| junk_silver | GET | Pre-1965 US 90% silver coin valuation by face value |
| goldback_price | GET | Goldback denomination pricing (½ to 100 GB) |
| gold_karat_value | GET | Gold jewelry/scrap by karat with refiner estimates |
| analyze_premium | GET | Grade a deal's premium A+ through D |
Example Requests
GET /api/gpt?action=spot_prices&metal=all
GET /api/gpt?action=melt_value&coin_id=morgan-dollar
GET /api/gpt?action=junk_silver&face_value=100&condition=circulated
GET /api/gpt?action=gold_karat_value&karat=14&weight=22&weight_unit=grams
GET /api/gpt?action=analyze_premium&purchase_price=38&weight_troy_oz=1&metal=silver
Try It Now
Select an action:
Known Coin IDs
Use these with action=melt_value&coin_id={id} for automatic weight and purity lookup.
morgan-dollar peace-dollar washington-quarter roosevelt-dime mercury-dime walking-liberty kennedy-half-90 kennedy-half-40 franklin-half barber-dime barber-quarter barber-half trade-dollar war-nickel silver-eagle silver-maple
gold-eagle-1oz gold-eagle-half gold-eagle-quarter gold-eagle-tenth gold-buffalo gold-maple krugerrand
platinum-eagle platinum-maple
AI Integrations
MetalMetric is available as a data source across multiple AI platforms.
MCP Server
Model Context Protocol endpoint for Claude and other MCP-compatible assistants. 7 tools, live data, zero auth.
POST metalmetric.com/api/mcp
ChatGPT Custom GPT
Published in the GPT Store as "MetalMetric — Precious Metals Assistant." Live spot prices and calculations inside ChatGPT.
Search "MetalMetric" in GPT Store
OpenAPI Spec
Standard OpenAPI 3.1 schema for any platform that supports API integrations. JSON format.
metalmetric.com/.well-known/openapi.json
AI Plugin Manifest
Standard ai-plugin.json discovery file for AI crawlers and tool registries.
metalmetric.com/.well-known/ai-plugin.json
Rate Limits & Usage
Rate limit: 30 requests/minute per IP Data refresh: Every 60 seconds from COMEX/LBMA Auth: None required Format: JSON (Content-Type: application/json) Methods: GET only (read-only, no mutations) CORS: Open (Access-Control-Allow-Origin: *) Free tier: Personal and non-commercial use Commercial: Contact [email protected]
FAQ
Yes. Free for personal and non-commercial use. No API key required. Rate limited to 30 requests per minute per IP. For commercial use, contact [email protected].
MetalMetric aggregates spot prices from COMEX (New York) and LBMA (London) global markets. Prices update every 60 seconds during market hours (Sunday 5pm – Friday 5pm CT).
Yes for personal projects. For commercial use or high-volume access, contact us. The API returns standard JSON and works with any HTTP client — fetch, axios, curl, Python requests, etc.
Yes. POST to metalmetric.com/api/mcp with JSON-RPC 2.0 messages. Supports 7 tools: get_spot_prices, calculate_melt_value, get_gold_silver_ratio, calculate_junk_silver, get_goldback_price, calculate_gold_karat_value, and analyze_premium.
Yes. Search "MetalMetric" in the ChatGPT GPT Store. It provides live spot prices, melt value calculations, and deal analysis directly inside ChatGPT conversations.
Track Your Stack
The API powers MetalMetric's free vault tracker. Add items, track cost basis, and see real-time P&L.
Open the Vault — Free