The Birthday application on Facebook has experienced incredible growth recently, but well-wishers may want to think twice before sending the gift to a friend. The app has grown from zero to nearly 2 million active users in the last two weeks, but there are quite a few negative reviews on the page claiming the app is a source of excessive spam.

Source: AppData

On the surface, the application seems pretty standard — a couple of gifts are immediately available to users, with several more unlocked when recipients accept your gifts. However, the language in the application could cause users to mistakenly send invitations to friends to “confirm their birthdays.” These factors are apparently resulting in a fairly large influx of spam, which has led to an extremely low user rating for the Birthday app and more than a few bad reviews from users.

Sending a friend a birthday gift laced with spam probably isn’t users’ intent. The developer also doesn’t reveal any information about themselves, with a faceless profile photo, no friends on their personal profile and no other applications or information available.

However, by developing an application purportedly around birthday messaging – a very popular activity on Facebook – Birthday was able to reach a large user number before word spread that it is spreading spam. It will be interesting to see how quickly users catch on, or if Facebook imposes any changes on the developer.