Micro-messaging service Twitter said this morning that it is banning third-party advertising in its stream, taking direct aim at Los Angeles-based Twitter advertising service Ad.ly. According to a post this morning from Twitter, the firm "will not allow any third party to inject paid tweets into a timeline on any service that leverages the Twitter API," essentially blocking automated advertising through Twitter streams by companies such as Ad.ly. Twitter said that third party ad networks are not necessarily looking to preserve the "unique user experience" of the site, and also said it came because it is looking to use its "Promoted tweets" to preserve the "integrity and relevance" of user timelines. Sean Rad, founder of Ad.ly, had yet to respond to requests for comments on the move. Ad.ly is backed by GRP Partners, Greycroft Ventures, and LowerMyBills founder Matt Coffin.
The move does not seem to affect the fortunes of Pasadena-based TweetUp, the new startup headed by Idealab's Bill Gross, as that firm's model does not rely on in-stream ads. TweetUp instead allows users to bid on keywords to promote their own tweets through other, non-Twitter web sites and search, and is not reliant on inserting ads into any Twitter stream. However, Twitter's own "Promoted Tweets" feature is direct competition to TweetUp's services.