More than 1,500 app developers in the United Kingdom brought a £785 million ($1 billion) class action lawsuit against Apple Tuesday over its App Store fees.
Revenues at Apple's services business, which includes the App Store, have grown rapidly in the last few years and now hover around $20 billion per quarter.
However, the commissions of 15% to 30% that the company charges some app makers for using an in-app payment system have been criticized by app developers and targeted by antitrust regulators in several countries.
Apple has previously said that 85% of developers on the App Store do not pay any commission and that it helps European developers access markets and customers in 175 countries around the world through the App Store.
The UK lawsuit at the Competition Appeal Tribunal is being brought by Sean Ennis, a professor at the Centre for Competition Policy at the University of East Anglia and a former economist at the Organisation for Economic Co-operation and Development, on behalf of 1,566 app developers.
He is being advised by law firm Geradin Partners.
"Apple's charges to app developers are excessive and only possible due to its monopoly on the distribution of apps onto iPhones and iPads," Ennis said in a statement.
"The charges are unfair in their own right and constitute abusive pricing. They harm app developers and also app buyers."