San Francisco, United States --- App revenue from mobile phone users around the world climbed to new heights in the first half of this year, nearly reaching $65 billion, market tracker Sensor Tower said Monday.

Apple and Google saw their respective mobile app shops thrive as the Silicon Valley giants remained under fire for the power they wield at their respective marketplaces.

Preliminary figures from Sensor Tower indicate that $64.9 billion was spent across the App Store and Google Play in the first six months of this year in a 25 percent jump fro the same period in 2020.

Sensor Tower projected that $41.5 billion would be spent at Apple's App Store during the first half of this year on subscriptions and apps, including in-app purchases such as virtual items for game characters.

Google Play was expected to generate a total of $23.4 in revenue by the end of June.

Video-snippet sharing sensation TikTok was the top grossing non-game mobile app, with users spending more than $920 million in a increase of 74 percent from the first six months of last year, according to Sensor Tower.

Google-owned video streaming platform YouTube was the second biggest non-game revenue generator, with users spending some $565 million there, the market tracker estimated.

Globally, spending in mobile games hit $44.7 billion in the first half of this year, up nearly 18 percent from the same period in 2020, according to Sensor Tower.

"While consumer spending in mobile games is growing at a slower clip than last year, this doesn’t indicate a downturn for the industry but rather a normalization after the surge in interest during the extraordinary circumstances of the Covid-19 pandemic," Sensor Tower said in a post.

Chinese internet titan Tencent had the top grossing mobile game, Honor of Kings, which generated more than $1.5 billion in the first half of this year, according to the market tracker.

The survey shows the growing importance of the so-called "app economy" and comes amid criticism over the tight control of the two large marketplaces by Apple and Google.

The Sensor Tower figures were released as a federal court mulls evidence presented during a trial in which Epic Games is trying to break Apple's tight grip on its App Store, and potentially disrupt the entire mobile ecosystem.

Epic, maker of the popular Fortnite video game, is seeking to force Apple to open up the App Store to third parties seeking to circumvent Apple's procedures payment systems and its commission as high as 30 percent in the process.