Finnhub API
Real-time REST and WebSocket API for stocks, forex, and cryptocurrency data, plus news, earnings, insider transactions, economic indicators, and sentiment analysis.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
HTTPS enforced on all endpoints. Header-based auth option (X-Finnhub-Token) avoids query parameter logging. Official Python SDK maintained by Finnhub with reasonable dependency hygiene. No scope granularity — single key grants full access. OpenAPI spec enables clients to implement proper security controls.
⚡ Reliability
Best When
An agent needs the best free-tier real-time data access with WebSocket streaming, alternative data (insider transactions, earnings surprises, news sentiment), and an OpenAPI spec for easy integration.
Avoid When
You need options data, very deep historical data, or are building a system requiring guaranteed uptime SLAs without an enterprise contract.
Use Cases
- • Real-time stock quote streaming via WebSocket for market-monitoring agents
- • Earnings calendar and earnings surprise tracking for event-driven trading agents
- • Insider transaction and institutional ownership monitoring
- • News feed aggregation with sentiment scoring for NLP pipelines
- • Economic indicator and macro data retrieval for macro-aware agents
Not For
- • Deep historical data beyond 30 years on free tier
- • Options and derivatives data
- • Guaranteed institutional-grade SLA without enterprise plan
Interface
Authentication
API key passed as query parameter (token=) or X-Finnhub-Token header. Header method is preferred for security. WebSocket authentication also uses the token parameter. No scope control.
Pricing
Free tier is the most generous among comparable financial APIs: 60 requests/minute allows meaningful agent workflows. Paid plans unlock global exchanges, extended history, and higher throughput. No credit card required for free tier.
Agent Metadata
Known Gotchas
- ⚠ Free tier limited to US markets — agents querying international symbols will get empty results without clear error
- ⚠ WebSocket connections require reconnection logic; no built-in heartbeat acknowledgment by default
- ⚠ Some endpoints have different data availability windows per plan tier (e.g., 1 year vs 30 years of history)
- ⚠ API key as query parameter leaks into logs; prefer X-Finnhub-Token header
- ⚠ Rate limit window is per-minute rolling, not per-second — burst traffic can trigger 429 unexpectedly
Alternatives
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Scores are editorial opinions as of 2026-03-07.