OfferUp is described as 'Buy. Sell. Simple. The largest mobile marketplace for local buyers and sellers. Great Deals. Better than Classified Ads' and is an app in the Online Services category. There are more than 50 alternatives to OfferUp for a variety of platforms, including the Web, iPhone, Android, iPad and Android Tablet. The best alternative is Amazon, which is free. Other great apps like OfferUp are eBay (Freemium), Aliexpress (Free), Etsy (Paid) and Newegg (Free).