Business leaders like Snap's Evan Spiegel and Barry Diller are conflicted about the App Store as Tim Cook takes the stand

• Barry Diller said Apple overcharges "in a disgusting manner" on its App Store.
• Spiegel said Snap is "happy" to pay the 30% fee and said the firm wouldn't exist without Apple.
• The comments come as Apple defends itself in a trial that focuses on if its App Store is a monopoly.

Business figures are split on Apple as CEO Tim Cook testifies in an antitrust trial focused on the App Store.

In separate interviews with CNBC on Friday, Snap CEO Evan Spiegel and Expedia Chairman Barry Diller came out swinging for and against, respectively, Apple as Cook took the stand.

Diller criticized Apple for using its "quasi-monopoly" to overcharge companies like his in "a disgusting manner" through its App Store commissions. The company requires developers to pay a 30% fee on purchases made in the marketplace, and many have long seen the practice as a way for Apple to obtain an unfair advantage in the market.

"The idea that they actually justify it by saying, 'We spend all this money protecting our little App Store,'" Diller told CNBC. "I mean, it's criminal. Well, it will be criminal."

Spiegel later spoke with the outlet and said Snap is "happy" to pay the 30% commission fee on in-app purchases.

"We really feel like Snapchat wouldn't exist without the iPhone and without the amazing platform that Apple has created," Spiegel said. "In that sense, I'm not sure we have a choice about paying the 30% fee, and of course, we're happy to do it in exchange for all of the amazing technology that they provide to us in terms of the software but also in terms of their hardware advancements."

Snap and Expedia did not immediately respond to requests for comment.

Read more: The App Store is Apple's most valuable asset, but also its biggest liability

Cook's Friday appearance on the stand comes as part of a trial that began earlier this month in California, prompted by a conflict between Apple and "Fortnite" creator Epic Games last summer.

Apple pulled the wildly popular "Fortnite" from its App Store in 2020 after Epic skirted the company's rules and fees to add its own in-app payment system. Epic has argued that Apple's App Store is a monopoly, while Apple says Epic simply broke the rules that govern its developers.

The trial is expected to conclude on Monday, and its results could majorly impact Apple's business.