The best open source alternative to Yahoo! Finance is Wealthfolio. If that doesn't suit you, our users have ranked more than 100 alternatives to Yahoo! Finance and five of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Yahoo! Finance are MarketMonk, SMA200 Tracker, StockTicker and ticker.
Wealthfolio is a simple, desktop-based investment tracker. Your financial data is stored safely on your own computer Ditch the spreadsheets, forget about those pesky subscription fees, and no more worries about SaaS services playing around with your data.
SMA200 is a free tool tracking whether US equities are trading above or below their 200-day simple moving average - a widely-used long-term trend filter. Access via web interface (sma200.trade/SYMBOL), JSON API, and an OpenAPI specification for programmatic use.
StockTicker - A resizable stock ticker widget for your android home screen, written in Kotlin
United States
focuses clearly on sma200 trend