OfferUp is a mobile app and website that allows users to buy and sell items locally. It provides a platform for individuals to list items they no longer need, such as furniture, electronics, and clothing, and connect with potential buyers in their area. Users can browse listings, negotiate prices, and arrange for safe transactions. The app features user profiles with ratings and reviews, helping to build trust within the community. OfferUp also offers a shipping option for items that can be sent to buyers outside the local area, expanding the marketplace beyond just local transactions.