As you know, the more people see your products, the better your chances of making a sale. To do that, you can upload products to marketplaces like Ebay, Amazon etc. But inventory synchronization can become a nightmare. This year we started using a SaaS product called Uploadmyproducts.com that pulls product data from our PHP based custom ecommerce site and uploads it to their database. From there, they push it to Ebay, Amazon, Google Shopping, Shopping etc. This helped synchronize our inventory across all marketplaces and now we are listing inventory and prices accurately. This helped us reduce order cancellations, improved feedback on marketplaces and our ratings on eBay.