Major app developers including Fortnite maker Epic Games and streaming music giant Spotify announced Thursday they had formed a coalition to press for new terms to the major online marketplaces operated by Apple and Google.

The announcement of the new Coalition for App Fairness advocacy group will seek legal and regulatory changes for the app stores which serve as gatekeepers for much of the mobile software distributed to consumers.

The move comes amid rising criticism of the fees and terms imposed by the app stores, and legal challenges by both Epic and Spotify to Apple's 30 percent commission for online subscriptions.

The new Washington-based organization also includes Match Group, which operates the Tinder dating service, software maker Basecamp, the French-based music service Deezer and the European Publishers Council.

The group appeared to focus on Apple, which has faced pressure in recent months for how it operates its App Store.

"As enforcers, regulators, and legislators around the world investigate Apple for its anti-competitive behavior, the Coalition for App Fairness will be the voice of app and game developers in the effort to protect consumer choice and create a level playing field for all," said Horacio Gutierrez of Spotify, which has filed an antitrust complaint against Apple in the European Union.

Tim Sweeney, founder of Epic Games, said the coalition aims to defend "basic freedoms" of developers are under attack.

"We are joining the Coalition for App Fairness to defend the fundamental rights of creators to build apps and to do business directly with their customers," said Sweeney, whose company has sued Apple after its efforts to circumvent App Store commissions resulted in its being kicked out of the online marketplace.

The group outline a set of principles for online marketplaces, saying no developer should be required to use one store exclusively or that company's payment systems.

The group also recommended that no developer be blocked based on how it delivers content and services, or whether it competes with the app store owner.

Apple had no immediate comment on the new organization. The company has argued in the past that its App Store has been a major source of economic activity and recently said it had some $519 billion in billings and sales globally in 2019.

Apple has also argued its fees are justified for monitoring safety and security of apps downloaded by iPhone users