Yahoo has acquired San Francisco-based video chat start-up company OnTheAir for an undisclosed sum. The move will help it compete with the likes of Skype and Google+ Hangouts as CEO Marissa Mayer continues her revamp of the technology giant.

The acquisition of OnTheAir is expected to help Yahoo develop and offer video chat apps for smartphones and tablets.

OnTheAir said in a statement that the company will be a good fit with Yahoo because of its focus on mobile, which is something Mayer has admitted Yahoo struggles with.

"When we first met the team at Yahoo, it was clear that everybody there is committed to making mobile products the backbone for the world’s daily habits. All in all, it’s a fascinating time to be joining Yahoo," the statement said.

Yahoo’s latest deal follows last month’s acquisition of mobile app Stamped, which the company reportedly acquired for $10m. Founded in 2011, Stamped offers a mobile app and website that allows users to share their recommendations with fellow users about restaurants, music, books and other things.