Absolutely, you can sell on multiple platforms like Etsy, Amazon, and eBay simultaneously. This is often referred to as multichannel selling. A 3PL service that offers multichannel fulfillment can manage your inventory and fulfill orders from all these platforms. When an order is placed on any of these platforms, you simply provide the necessary information to the 3PL service, and they handle the rest. They pick, pack, and ship the order to your customer. They also provide you with tracking information, which you then add to the respective platform. This allows you to manage your inventory and orders from multiple platforms in one place, saving you time and effort, and allowing you to focus more on growing your business. However, you would still need to manage the listings, customer service, and other aspects of your business on each platform separately.