When Twitter bought Mixer Labs in December, 2009, it inherited the startup's then-recently launched GeoAPI , which offered a platform for building geo apps. The GeoAPI combined a places database of 16 million businesses with a reverse-geo-coder and support for geo-coded Tweets, Flickr photos, and even an iPhone SDK. Twitter kept the GeoAPI going after the acquisition—but that ends at the end of March. According to a developer who used to build his product on the GeoAPI, Twitter is shutting it down for outside developers. It is too much of a hassle to maintain, apparently. Twitter will still use it internally for its own apps. (Note that this GeoAPI is not the same as Twitter's more limited Geotagging API , which is still fully functional). So far no announcement on this. It's going in the deadpool . I've reached out to Twitter for a comment.