yfinance

Overview

yfinance is an open-source Python wrapper for Yahoo Finance, providing global market data (US, HK, and Canadian stocks, ETFs, indices) including historical and real-time quotes. Completely free, no registration or API key required.

The project has a built-in yfinance DataLoader (backtest/loaders/yfinance_loader.py). When backtesting, set source: "yfinance" or source: "auto" to invoke it automatically.

For OHLCV bars in agent/swarm work, prefer the get_market_data tool when it is available. It routes through the project loader layer, normalizes symbols, removes malformed OHLC rows, and returns strict JSON. Use direct yfinance calls mainly for data outside OHLCV coverage such as company info, financial statements, options, holders, and insider transactions.

Deep Yahoo Interfaces (references/)

Beyond the yfinance package, the project ships a built-in Yahoo public-API client (backtest.loaders.yahoo_client) and two read-only agent tools that sit on top of it. These reach Yahoo's own unauthenticated JSON endpoints directly via requests (no yfinance install needed), share one throttled HTTP gate (Yahoo rate-limits by source IP), and handle the cookie+crumb handshake automatically. Each interface has its own reference doc — read the one you need rather than loading them all: