5miles - Online marketplace with ability to be localized.
Amazon – Aside from eBay, probably the best selection of products online.
Carousell - Setup and join communities of buyers and sellers.
Chairish - Kind of an online consignment retailer that also provides other services like managing online payments or arranging delivery to local shops.
Craigslist – Connecting local communities to buy and sell items.
Decluttr - Specializing in CDs, DVDs, games, books, game controllers, and cellphones.
Depop – An app-based marketplace with an emphasis on building your own community to share your offers and purchases.
eBay – You name it; it’s probably on eBay.
Etsy – One of the first homes for creative gifts and independent sellers
Facebook – Did you forget about Facebook Marketplace? You wouldn’t be the first – this is a great place to peddle your wares (and services) locally. Also, you have a kind of built-in reference system if you’re dealing with a friend of a friend
Gazelle – One of the de facto places to see how much your smartphone and other gadget is actually worth.
Gone – Electronic selling app specializing in wearables, phones, laptops, tablets, and e-readers.
Hoobly - Online classifieds from all over the world
letgo – A fairly new player in the online marketplace landscape (founded in 2015), this startup relies on simplicity : snap a picture, post, chat, buy or sell. Bam. BTW, letgo merged with Wallapop in mid-2016.
Listia – You sell your items not for cash, but for credits. Use earned credits to buy other things on the site, or cash them in for money.
Offerup – Another app-based mobile marketplace very similar to letgo.
Poshmark – General fashion.
Shopify – An online portal to help you set up your ecommerce business.
The Real Real –Consignment for luxury brands.
Tradesy – Luxury brands; guaranteed authenticity.
Trove -Buy and sell used furniture online.
VarageSale – “Varage” is a mashup of virtual and garage. Get it? It’s a virtual garage sale that uses your Facebook profile to connect with other members. Members can meet up for individual sales or do a group flea market flash-mob style.
Vinted - De-clutter your closet and sell your clothing online.