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.

Of course, Twitter has no obligation to keep maintaining the API. But the shutdown may be taken by developers as yet another sign that Twitter is not to be relied upon, and doesn’t have their best interests at heart. Oh well, there still SimpleGeo and Factual.

Update: Originally I reported that the GeoAPI was shut down yesterday but Twitter just got back to me and clarified that it will shut down on March 31. Twitter also says it already migrated most of the functionality over to the Twitter API, but the developer I spoke to decided to swap it out for a competing API because of the lack of support. If you are a geo developer, what do you think? Is Twitter API as good as the old GeoAPI or competing geo APIs? Enlighten us in comments.

Here is the email Twitter sent to developers last December: