Amazon is a highly recognized global brand when it comes to online shopping. Amazon shoppers can search through a huge catalogue of new, used, refurbished and collectable products from a range of sellers. Integration is simple, and if you're selling items already listed in their catalogue, you can quickly become one of their alternative sellers.

Google Base allows users to submit products for free via a product feed or using the Google Base API. You can add multiple attributes to your products so that online visitors can find your products more efficiently in related searches. Your products may also appear in search results on Google Search and Google Maps.

Why not sell your products through social media giant Facebook? All you need is a Facebook Fan Page and a Google Merchant Center data feed and you could integrate with your online store. Facebook has over 500 million users worldwide and you can spot their social sharing icons almost everywhere.

Shopping.com is a well-established Marketplace with around 20 million unique users per month. It offers simple search tools and navigation, appealing content and millions of product and retailer reviews. You can list your products on Shopping.com for free and you will only pay for qualified leads to your store.

Kelkoo is a product comparison website aimed at shoppers who value user advice higher than price. It's often the place where shoppers looking to research their products will start their journey as it provides millions of product user reviews and instant feedback from aggregated ratings scores. Kelkoo has 32 million unique users across multiple countries and will only charge you as the merchant when a user clicks through from their site to your online store.