Colnect is described as 'marketplace, collectors community, and catalogs of mass-produced collectibles: stamps, coins, sports cards, phone cards and other 29 categories. Colnect marketplace allows using catalog description of the item in the sale details'. There are three alternatives to Colnect, not only websites but also apps for a variety of platforms, including Windows, Windows S, Android and Android Tablet. The best alternative is eBay, which is free. Other great sites and apps similar to Colnect are BuyBest.One (Free) and Particl Marketplace (Free, Open Source).