Goldprice.dev vs Portfolio Optimizer

Goldprice.dev is a commodity-pricing API returning live XAU/XAG/copper spot prices across 31 currencies (cross-checked via exchangerate.dev with an ECB fallback), COMEX gold futures and GLD ETF data, and over a decade of daily XAU/USD history, with every price citing its source and published methodology. Access is anonymous and keyless by default at a modest rate limit; a free API key raises throughput, and paid tiers add per-country physical dealer pricing, a volatility/probability surface, a real-time SSE/WebSocket feed, and an MCP server on every plan. A live Origin-header probe against the real API host (api.goldprice.dev) found no Access-Control-Allow-Origin header, so CORS resolves to `no` — the stored `unknown` was unresolved, not confirmed open.

Portfolio Optimizer is a free, no-signup Web API implementing modern-portfolio-theory algorithms — mean-variance and minimum-variance optimization, risk and performance analytics, backtesting, and factor-model tools — over JSON, so it can be called from Python, Excel, Google Sheets, or any HTTP client without an SDK. The homepage explicitly advertises free access with no registration required, and a live test against a real optimization endpoint (api.portfoliooptimizer.io) returned `Access-Control-Allow-Origin: *` on both a route-not-found and a malformed-payload response, confirming CORS is enabled; the same responses carry a `WWW-Authenticate: Key` header hinting at an optional key for higher throughput, though the observed default rate limit is a modest 1 request/second.