State of Financial Data APIs -- March 2026: How Agent-Ready Is Your Data Provider?

AI agents are the fastest-growing consumers of financial data APIs. They need machine-readable docs, predictable auth, stable schemas, and honest rate limits. We audited 10 of the most popular financial data APIs to find out which ones are ready for the agent era -- and which ones are still stuck in 2022. This is Report #1 in a monthly series from OathScore . Starting in April, we'll publish full composite quality scores (0-100) based on 30 days of continuous monitoring. This report covers what we found while building the monitoring system. The 10 APIs We Audited Alpha Vantage -- Equities, macro, forex (25 req/day free, from $49.99/mo) Polygon.io / Massive -- Market data (5 req/min free, from $29/mo) Finnhub -- Multi-asset, calendar, alt data (60 req/min free, from ~$50/mo) Twelve Data -- Market data, forex, crypto (8 req/min free, from $29/mo) EODHD -- Historical data (20 req/day free, from EUR 19.99/mo) Financial Modeling Prep -- Fundamentals (250 req/day free, from $19/mo) FRED -- F