If you're an eBay seller using a third-party service, are you wondering why you're paying more in auction service fees? One reason could be that you are making up the Application Programming Interface (API) license fees that eBay is charging third-party vendors for special access to its site. eBay's API provides a way for third parties to access eBay data. Many high-tech companies provide API to software developers, though not all of them charge for doing so.

While vendors can access eBay without the API, it makes updating their information more difficult, since eBay makes continuous changes to its site. As an example, every time eBay adds a new category, vendors must update the information on their tools to reflect the changes. Companies that interact with eBay include auction-management software vendors and e-commerce sites that upload auctions to eBay.

Participating in eBay's API does not always ensure smooth sailing. When eBay implemented its Checkout features in October of 2001, it caused havoc with the checkout features of third-party software vendors - even vendors participating in eBay's API program. And on a recent "Free Listing Day" on eBay last December, some licensed vendors had trouble uploading listings to eBay.

Vendors must apply for the program and pay eBay an annual charge plus per-access charges. eBay has three levels for their API subscribers:

-Bronze $1,000 per year PLUS $6.50 per 1,000 API calls

-Silver $5,000 per year PLUS $3.15 per 1,000 API calls

-Gold $10,000 per year PLUS $2.90 per 1,000 API calls

eBay also requires products to go through an independent certification process, for which there is a fee of $5,000.