As BlackBerry and Windows slowly augment their apps catalogues to challenge Apple’s iOS and Google’s Android – and growth continues in the tablet market – ABI Research projects the mobile app market will be worth $27 billion in 2013.

BlackBerry and Windows, however, are still far behind Google and Apple in the mobile apps space.

“iOS continues to lead the way, and the OS is projected to generate over two-thirds of the revenues for smartphone and tablet apps in 2013,” said senior analyst Josh Flood.

“Although Google’s Android OS recently surpassed Apple in terms of total app numbers, iOS users continue to prove they’re more willing to part with their cash. The revenue gap between the two leading OSes looks unlikely to close over the next 18 months.”

ABI Research adds that app revenues generated from smartphones have significantly dwarfed app revenues from tablets. However, tablet revenues are quickly catching up. The research firm projects that tablet app revenues will overtake smartphones by 2017.

Tablet users tend to pay more for apps than smartphones owners because of the larger screen size and better user experience for gaming and reading, says ABI Research.