Instagram has tweaked its spam filtering techniques for a second time this week. The side effect of the changes has allowed third-party Windows Phone apps to once again upload photos to the service unofficially. Instagram updated its spam filters on Tuesday, resulting in existing photos from third-party apps being blocked from public view, and fresh uploads deleted from the service within seconds. It initially appeared to be an effort to block third-party apps, but an Instagram spokesperson revealed to The Verge that the change was spam-related and did not "specifically target any particular app or platform."

The new spam changes don't appear to be as aggressive as the initial update, but any alterations could be temporary. The Verge understands that Facebook regularly updates its anti-spam techniques, so any changes could affect third-party apps that aren't using official APIs. We've confirmed that photos uploaded using third-party Windows Phone apps are now publicly visible, and new uploads are working. It's not clear how temporary this latest spam filter change is, and it's possible that third-party access could inadvertently be blocked once again in future updates.

The risk of relying on unofficial apps

Instagram's changes highlight the risk of using third-party apps that do not have official access to the APIs of the services they connect to. These applications can break at random, and developers are often stuck in a cat and mouse game trying to catch up and fix issues from any changes. Popular Windows Phone YouTube app MetroTube faces similar issues regularly, with the third-party app breaking when Google alters its APIs. Instance, and other unofficial Instagram clients are working for now, but until Facebook builds its own official Windows Phone app — or opens up its API — these third-party versions will always run the risk of breaking at random.