About thirty percent of all eBay listings are posted by third-party developers using eBay Web services. eBay created the Developers Program to assist third-parties in helping buyers and sellers shop and sell on eBay more effectively. As the program turns 7 years this month, AuctionBytes takes a look back at how the program evolved over the years.

eBay launched a beta version of the API (Application Programming Interface) in November 2000 and opened it up in Spring 2001 in a contained way. Prior to the launch of the API, third-party vendors had to "scrape" the eBay website in order for them to help their customers buy and sell on the site, and it wasn't until 2004 that eBay created a "token" authentication system for developers so they would no longer have to ask customers for their eBay passwords. In July 2005, eBay launched Community Codebase to foster open-source developer collaboration.

In the early days of the program, vendors had to pay a sizeable upfront fee to go through the certification process and then paid an annual fee plus monthly usage fees. Two years ago, eBay eliminated third-party developer fees (they still pay for support, however).

In 2002, there were 200 companies who were API-certified. Today, over 60,000 developers have registered as members of the eBay Developers Program, and there are nearly 10,000 live applications. Over 5.7 billion API calls are made every month.

Traditionally, most developers joined the program to build selling tools, and charged sellers fees for using them. In 2007, eBay set out to encourage developers to create tools for buyers in conjunction with its "Disruptive Innovation" program, creating buy-side API calls and showing developers how they could generate revenue through the eBay Affiliate program.

eBay users can search for third-party developers in the Solutions directory (http://solutions.ebay.com).