This is an attempt to map merchant-immutable marketplace categories to each other for the express purpose of using this to programatically add listings to each channel in bulk.
Basically, the idea of having 20,000 listings on one sales channel but still having to cross list them individually on another sales channel doesn't make much sense as far as efficiency. For example, if I have 1,000 widgets that are all in the same category on Amazon Marketplace, why can't I map that Amazon category to an eBay category, press a button and publish all 1,000 listings to eBay. This is a huge time saver and possibly a game changer.
Disclaimer: This isn't going to be an exact science. I understand that others may or may not agree with the mappings I use and vice versa, however, I feel it's better to begin the dialogue, so to speak, to see if there is a way to standardize the marketplace categories.
Currently, this respository includes many Amazon and eBay categories.