Instagram Blocking Third Party Upload Clients

The Verge:

While Vine, Flipboard, and Path have all promised Windows Phone 8 support, one particular app is still missing: Instagram. Nokia has tried to pressure Facebook into building an Instagram Windows Phone app, but so far users have had to resort to third-party applications. Instance, a popular unofficial Windows Phone Instagram app that supports viewing and uploading of Instagram photos, appears to now be blocked from using the photo sharing service. The application reverse engineers Instagram’s own API to bypass and upload pictures to the service unofficially.

Why is this news? This is a private API which means others aren’t supposed to use it.