IEX Cloud API
Real-time and historical stock market data API providing quotes, financials, earnings, news, crypto, and forex data via REST and SSE streaming.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
HTTPS enforced. However, API key as query parameter is a security anti-pattern that leaks tokens into server logs and browser history. No scope granularity on free/mid tiers. Publishable token concept helps client-side use cases.
⚡ Reliability
Best When
An agent needs consistent, well-structured US equity data with real-time quotes and fundamental financials from a single endpoint.
Avoid When
You need tick-by-tick Level 2 order book data or are building high-frequency trading infrastructure.
Use Cases
- • Real-time stock quote retrieval for portfolio monitoring agents
- • Fundamental data analysis (earnings, financials, balance sheets)
- • News and sentiment aggregation for trading signal agents
- • Cryptocurrency and forex rate lookups
- • Historical OHLCV data for backtesting pipelines
Not For
- • Ultra-low-latency trading requiring sub-millisecond data feeds
- • Options chain data or derivatives analytics
- • Non-US exchanges on lower-tier plans
Interface
Authentication
Single API token passed as query parameter (token=) or Authorization header. Separate publishable vs secret tokens for client vs server use. No fine-grained scope control.
Pricing
Credit-based system where each endpoint costs a different number of messages. Real-time data and premium datasets cost more credits. Free tier has no credit card requirement.
Agent Metadata
Known Gotchas
- ⚠ Credit consumption is endpoint-specific and not obvious at call time; agents can exhaust credits unexpectedly
- ⚠ API token passed as query parameter is logged in server access logs by default
- ⚠ SSE streaming endpoint requires persistent connection management not native to simple HTTP clients
- ⚠ Some endpoints return empty arrays vs null for missing data inconsistently
- ⚠ Free tier message limits reset monthly, not rolling 30 days
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for IEX Cloud API.
Scores are editorial opinions as of 2026-03-06.