Like neighbor Apple, Facebook is unafraid of flexing its muscles with third-party application developers, shutting down several applications over the past few days, according to posts on its developer forum and several social networking sites.

Facebook, which has more than 500 million users, on Wednesday blocked Breakup Notifier, independent developer Dan Loewenherz wrote on the application's Facebook Fan page. The tool, which allowed users to keep up-to-date about changes in their friends' relationship status, had hit 3.6 million users since its debut on Monday, according to Breakup Notifier.

"Hey everyone, so we just received an email from Facebook saying they've shut our app down, we're doing everything we can to try and get this back online and working for you. We need to talk to them and would ask that you guys give us your support during this extreme growth phase," the company posted Wednesday morning on its Facebook fan page . "Thanks for your help, support, and patience and I promise we're working as hard as we can for you to enjoy this! Thank you! Be back up soon!"

Loewenherz told InformationWeek, "We still don't know why Facebook did this, and they haven't told us what we need to do to restore our application. [Any] [p]re-launch testing? hahah, not really. I had no clue that it would become this big."

In response to a request for comment, a Facebook spokesperson emailed the following statement to InformationWeek: "Breakup Notifier was temporarily disabled by one of our automated systems, which we have in place to ensure apps on Facebook Platform provide positive user experiences. These systems have worked well, cutting spam by 95% last year alone. We're currently looking into the issue and have reached out to the developer."

On Thursday afternoon Breakup Notifier posted on its fan page that the social network was working to restore API access to it.

Both Apple and Facebook enforce such stringent requirements because the stakes are so high: Revenue for games and applications will increase to between $2.60 and $5 per registered user by 2017, according to Trefis. With the unlikely scenario of zero membership growth, that means Facebook could reap revenue of between $1.3 billion and $2.5 billion on games and apps alone.

Last week, app developer Danny416 posted a letter in Facebook's Developer Forum he had submitted to Facebook Platform regarding a poker application, ID 194287413934599, that had been disabled. The developers had paid $1,617 for Facebook ads to quickly reach users for the multi-player application, and received more than 50,000 clicks and about 15,000 installs, he said. Within 12 hours, Facebook disabled the app, said Danny 416.

"The app was not forcing the users in any way to spam. For every action in the game that a user might want to share we display a pop up with two option: skip and share. If a user clicks share we display the facebook window to allow the user to customize the post. Again the user has the option to either skip or post," he wrote. "We strongly believe that facebook bot made a huge mistake which affected us financially and mentally. Our stats show that 90% of our installs came from facebook ads, 5% from invites, and about 4% from shares.

"This is extremelly frustrating because we have no intention of spamming facebook or gathering users through illegal means, otherwise we would not invest so much money in facebook ads," Danny416 continued. "We appealed to facebook and waiting for a resolution to this issue. We understand that on facebook are created 1000s of apps every day with the only reason to spam facebook and measures must be taken by facebook, however our app had no such intentions. Facebook charged us for the installs and banned our app."