People in China may be barred from accessing Facebook, but that hasn’t stopped them from making software for the 845-million member social network.

The partnerships with Chinese software developers allow Facebook to find ways to show investors in its upcoming initial public offering growth and expansion in China, even though the Chinese government has banned access to the site since 2009. The Chinese game developers could also be a strong source of revenue growth for the recent addition of advertisements to Facebook’s mobile site.

Facebook reported that China is its largest Asian software partner, with about one in five of the apps being developed by its Asian partner network being developed in China. David Lim, in Facebook’s mobile developer relations division, told Bloomberg News Chinese developers are using the social network to reach overseas markets.

“Developers in mainland China are important to us,” Lim said at the World Internet Developers’ Summit.

Facebook has been spending heavily to attract outside developers: also on Monday, the company said it spent $1.4 billion on outside developers last year, with much of that spending going towards game development. The company went from having no people dedicated to gaming in 2010 to now having 40 employees working full-time on game development.

Facebook’s two biggest competitors in the social networking space, Google+ and Twitter, are also banned in China. Google+ recently renewed expansion efforts into China, but recent crackdowns on users of Twitter-like microblogging services, including requirements that all users register with the government, could present problems as all three look to expand into the lucrative market.