Verdict: Alpha Vantage is the easier starting point for REST-based prototypes and pre-computed indicators. Polygon.io is the stronger fit when WebSockets, flat files and a production-oriented market-data pipeline matter.
Free plans
Alpha Vantage permits 25 requests per day. Polygon.io’s free stock plan permits five calls per minute and includes two years of history. Both work for testing, but neither should be selected without estimating the full call pattern of the intended application.
Paid pricing and real-time data
Alpha Vantage starts at $49.99 per month for 75 requests per minute and 15-minute delayed US stock data. Its eligible real-time US stock entitlement begins at $99.99 per month. Polygon.io starts at $29 per month for unlimited calls and delayed stock data; its $199 Advanced stock plan is the first individual tier with real-time US stock data.
The providers package access differently. Compare the precise asset class, latency, request capacity, historical depth and redistribution rights—not only the lowest subscription price.
Delivery model
Alpha Vantage is REST-focused and provides many indicators as ready-made endpoints. Polygon.io provides REST APIs, WebSockets and downloadable flat files, giving developers more delivery choices for sustained pipelines and streaming applications.
Which should you choose?
- Choose Alpha Vantage for learning, small research scripts and fast indicator prototypes.
- Choose Polygon.io for WebSocket workflows, downloadable market files and deeper stock-data infrastructure.
- Choose neither yet if you have not documented latency, exchange, options, commercial-use and redistribution requirements.
Read the full Alpha Vantage review and Polygon.io review for current plan details and first-party sources.