How to Compare Free Market Data APIs
Not financial advice. Verify claims independently.
A checklist for rate limits, freshness, coverage, and licensing before choosing a data source.
This is an evaluation checklist, not an independent benchmark. Provider plans and permissions change, so verify the current documentation before building against an API.
Inspect the essentials
| Question | What to record |
|---|---|
| Rate limits | Requests per interval, burst rules, and retry guidance |
| Freshness | Delayed, end-of-day, or real-time; the timestamp definition |
| Coverage | Instruments, exchanges, history, and corporate actions |
| Reliability | Error behavior, pagination, and status reporting |
| Permissions | Display, redistribution, retention, and commercial-use terms |
Run a small evaluation
Choose a documented endpoint and a small symbol set. Save request times, response timestamps, and errors. Test missing symbols and throttling behavior before connecting the result to a dashboard.
Keep research separate from production
A prototype may need only a limited dataset. A customer-facing application also needs clear licensing, failure handling, and a support plan. Do not infer redistribution rights from the fact that an endpoint is accessible.
Rankings and specifications are editorial — verify current terms with each provider.
Put it into practice
Rehearse this strategy risk-free on Stock Picks — the reference free paper-trading tool listed in the Mkts/Apps field manual.
Open Stock Picks →