Amazon, eBay, Etsy, etc. are some of the popular eCommerce sites. These sites have huge traffic and registered buyers. Therefore, you can also use these sites to build an income. Interestingly, you do not have to do a lot of work to build an income on eCommerce sites, therefore, it si completely passive income. Once you list your products for sale, you will have to run ads on these eCommerce sites or social media platforms to generate sales, and you will start making money on auto pilot.