Most people searching for free stock data end up in the same loop. They find Yahoo Finance. The yfinance library seems perfect — until it breaks in production, returns inconsistent data, or silently changes its response format because it's scraping an unofficial endpoint. Then they try pandas-datareader. Then Alpha Vantage with a key that throttles after 5 requests per minute. Then a random GitHub repo with 200 stars and no commits since 2022. If you're: building a backtesting engine, training a financial ML model, or just trying to get clean OHLCV data without paying enterprise prices, this matters. The real problem isn't that free historical stock data doesn't exist. It's that most free options are brittle — they work in a Jupyter notebook and fail the moment you put them in a real project. Why Unofficial APIs Break (and What to Use Instead) yfinance is the most-used Python library for historical stock data.…