Amazon, Lendle and the Danger of Using Open APIs

Updated: Lendle, an ebook-sharing service that allows users to find and trade Kindle books, sounds like a great idea — except that it doesn’t work anymore, because Amazon (s amzn) pulled the plug on the site by blocking access to the Amazon API. According to Lendle co-founder Jeff Croft, there was no warning from the online retailer, only a cryptically worded email. So Lendle becomes the latest poster child for a simple maxim: Building your service on top of someone else’s API, no matter how “open” the API is supposed to be, is a very dangerous road.

Update: Lendle has posted an update on its blog to say that it has modified its service as requested by Amazon (removing a feature that allowed Lendle users to synchronize their books with their Kindle account) and API access has been restored. However, the company also said that as a result of the incident it had “come to realize we need to work towards a Lendle product that does not rely on APIs provided by Amazon or any other third party.”

No one knows the downside of this approach better than Bill Gross, the founder of UberMedia, which the veteran Silicon Valley entrepreneur has built into a kind of Twitter client rollup by acquiring services and apps such as UberTwitter and Echofon. Gross originally had a great idea for selling advertising around tweets as well, but then Twitter launched its own identical advertising platform. Earlier this year, after what Twitter said was bad behavior by some of UberMedia’s apps, the social-media platform shut down the company’s access to the Twitter API.

In UberMedia’s case, the company made some changes to its apps, and Twitter turned the API tap back on. It’s not clear whether Lendle will be able to modify the way its service works to make Amazon happy, however. The online retailer hasn’t made any statement about the action it has taken against the ebook-lending service other than to say┬áLendle doesn’t “serve the principal purpose of driving sales of products and services on the Amazon site.” We’ve emailed Amazon and will update this post if there is any response.

Is Amazon planning its own lending service, or is it simply afraid that more borrowing of books equals less buying? The answers to those questions remain unclear until the company clarifies its reasoning (Lendle says users buy more books after borrowing them).

Twitter used to be the most obvious example of a company that was willing to let developers do pretty much whatever they wanted with the service’s data, and that open approach arguably helped to create much of the network’s value, including popular conventions such as the retweet, the @ mention and so on. But Twitter has been tightening the reins on what it allows for some time now, and its latest pronouncement made it clear certain aspects of its business are simply off-limits for third-party developers.

In some ways, that’s a natural evolution for a company: to be open with its data when it is trying to grow, then to shut down or restrict that as it tries to become a functioning business and make money. Amazon has long since passed that point, of course, and Lendle is only the latest to find out that what it thinks is a good service and what a company like Amazon thinks can be two very different things — and whoever controls the API wins.

Post and thumbnail photos courtesy of Flickr user Will Clayton