Google Inc. has opened up its Google Plus social network to everyone after testing it with a limited audience for 12 weeks.

Google said in a blog post Tuesday that it will now let anyone sign up for Google Plus. Previously the service was only available by invitation, though it got easier to join in recent weeks.

The company also added a search capability to Google Plus that will let users sift through posts on the site.

Google Plus is the online search leader's attempt to compete with Facebook, by far the world's most populous online social network with more than 750 million users. Tuesday's upgrades come two days ahead of Facebook's f8 conference in San Francisco, where the company is expected to unveil several new features.

Google also made Plus's "Hangouts" feature — which lets users video chat with multiple people at a time — available on smartphones with front-facing cameras. The feature currently works with phones running Google's Android system. Google says support for Apple devices is coming soon.

A new service called "Hangouts On Air," meanwhile, lets users broadcast their videos online or view these videos as spectators.

Google said it's starting off with a limited number of broadcasters. Google plans to host its first such hangout with Black Eyed Peas frontman Will.i.am. on Wednesday night.