DealSonar watches Facebook Marketplace and Vinted for you and pings you the moment a profitable listing appears. Set a monitor once (keyword, price range, condition, location radius) and DealSonar does the rest: AI filters out junk and wrong models, eBay sold comps show what the item actually sells for, and a profit calculator does fees and postage before you message the seller. Alerts via email, Discord, or Telegram.