Marketstack API
REST API for end-of-day and intraday stock market data covering 70+ global exchanges, providing OHLCV, splits, dividends, and ticker metadata.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Critical: free tier uses HTTP not HTTPS, sending API keys in plaintext. HTTPS is a paid feature, which is unusual and problematic for security-conscious users. No scope granularity. API key as query parameter leaks into server logs. No official SDK to audit.
⚡ Reliability
Best When
An agent needs clean, consistent historical OHLCV data across global exchanges with minimal setup at low cost.
Avoid When
You need real-time data, fundamental financial data, or more than 100 requests per month without paying.
Use Cases
- • Historical EOD price data retrieval for financial analysis agents
- • Multi-exchange portfolio valuation across global markets
- • Dividend and stock split event tracking for portfolio management
- • Simple OHLCV data ingestion for ML training pipelines
- • Ticker metadata and exchange listing lookups
Not For
- • Real-time streaming quotes (EOD focus, intraday only on paid plans)
- • Fundamental data (no earnings, balance sheets, or financials)
- • News, sentiment, or alternative data
Interface
Authentication
API access key passed as query parameter (access_key=). HTTP only on free plan; HTTPS requires paid plan. Single key with no scope control.
Pricing
Free tier is HTTP-only, which is a significant security concern for production use. HTTPS requires paid plan. Monthly request caps can be hit quickly in agent workflows.
Agent Metadata
Known Gotchas
- ⚠ Free tier uses HTTP not HTTPS — never use free tier in production agents handling sensitive data
- ⚠ 100 requests/month on free tier is exhausted in minutes by any non-trivial agent workflow
- ⚠ No official SDK — agents must implement HTTP client logic directly
- ⚠ Intraday data (real-time) only available on paid plans
- ⚠ Rate limit errors may not be clearly distinguished from other 4xx errors in all cases
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for Marketstack API.
Scores are editorial opinions as of 2026-03-06.