Facebook has raised the bar for application developers – creating new rules for applications with more than 5 million active monthly users. Previously the additional requirements only kicked in for applications with more than 5 million active daily users.

The terms on the Facebook Developer Principles & Policies page have been updated with the following clause:

“If you exceed, or plan to exceed, any of the following thresholds please contact us as you may be subject to additional terms: (>5M MAU) or (>100M API calls per day) or (>50M impressions per day).”

A Facebook spokesperson told Inside Facebook the move was prompted by the need to maintain quality service on the Facebook Platform.

“We recently revised our threshold policy from 5 million daily active users to 5 million monthly active users,” the spokesperson said. “We want to work closely with our largest developers in order to maintain a high level of performance, speed and uptime for Facbook Platform. Sudden, unexpected large increases in API usage could negatively impact both developers and users.”

The additional requirements for large application developers are undisclosed but AllFacebook understand they are related to site performance. With the social networking site recently reaching 500 million users, maintaining stability of the platform as the user base grows is a key challenge for Facebook’s network engineers.