Sello - Sello is the simplest way to sell online.
Facebook Marketplace - Marketplace is a convenient destination on Facebook to discover, buy and sell items with people in your community.
5miles - 5miles isn’t just a buying & selling app. It’s a way to become a better neighbor. Buy & sell used cars, furniture, electronics or offer services like beauty, auto repair, and home cleaning locally using the 5miles app.
craigslist - craigslist provides local classifieds and forums for jobs, housing, for sale, services, local community, and events
Backflip - Selling your electronics just got easy
Fobo - Forget Craigslist, use this to buy/sell electronics (SF)