SparkFin - Learn the markets for free, profit forever.
Alpaca - Open links from Slack via desktop apps: Notion, Spotify, Zoom, Miro, Telegram, Airtable, Figma and VK.
Robinhood - Free stock trading service.
Bullish.email - The Stock Market in your inbox every morning
StockTwits - A financial communications platform for the investing community.
StockData.org - Free real-time, intraday and historical stock market, crypto and forex JSON APIs.