Alpaca vs Portfolio Optimizer

Alpaca's Market Data API v2 delivers realtime and historical quotes, trades, and bars for US equities and ETFs over REST and WebSocket, requiring an Alpaca brokerage/API-key account. The free plan gives 200 API calls/minute with 15-minute-delayed IEX-exchange data and 30-symbol WebSocket streams; the $99/month Algo Trader Plus tier removes the call cap, adds true realtime data from all US exchanges (plus real-time OPRA options quotes), and unlimited streamed symbols. Both tiers include 7+ years of historical data.

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.