Facebook F8 Mark Zuckerberg
Facebook CEO Mark Zuckerberg at the social network's annual F8 developer conferenceScreengrab

Facebook has opened up its messaging app to third-party apps, allowing developers to add functions like e-cards, weather forecasts and GIFs through Messenger Platform.

Facebook founder and CEO Mark Zuckerberg made the announcement at the social network's annual F8 developer conference on Wednesday 25 March.

"This is a really exciting big new area and opportunity," Zuckerberg said. "We're really excited to see what people do with this."

By opening itself up to allow instant third-party app integration, Messenger lets users send messages in new formats like GIFs.

"I find GIFs really awesome," said David Marcus, vice president of Messaging products at Facebook. "They just make the world a bit better.

"All of us on the Messenger team are really excited because we really believe that we can change the way people communicate every day."

Around 40 add-ons have already been developed for Messenger, available for the 600 million people who use Messenger every month.

One new tool for Messenger allows users to track online purchases through a single thread on the app, rather than receiving a string of emails from the merchant.

Zuckerberg also spoke about the evolution of messaging: from text, to images, to videos, and beyond towards virtual reality. Oculus Rift announcements are also expected at F8, which runs until Thursday 26 March.

"Right now we're at this interesting transition where we're beginning to see video interspersed with elements of virtual reality," Zuckerberg said. "So soon we're going to start including spherical videos to the news feed."