Tile, Spotify, and Match representatives had to testified, accusing the two tech companies of charging exorbitant fees and plagiarizing their inventions.
Both Apple and Google’s app stores charge fees of up to 30% for in-app purchases.
The two companies said the fees were justified to provide security for users.
The antitrust panel of the Senate Judiciary Committee looked at allegations that Apple’s App Store and Google’s Google Play are anti-competitive.
Senator Amy Klobuchar said that Apple’s App Store was a “literal monopoly”.
She said both stores “exclude or suppress apps that compete with their own products” and “charge excessive fees that affect competition in the app store economy”.
Google Play and the App Store are where the vast majority of apps worldwide are downloaded.
Developers claim that because of a lack of competition Apple and Google can charge extortionate rates.
Tile’s General Counsel Kirsten Daru said “We welcome competition but it has to be fair competition and Apple’s idea of competing is patently unfair.”
She also accused Apple of preventing Tile from using the technology behind Apple’s Find My function, giving AirTags an unfair advantage.
Apple said the product was different. “We didn’t copy Tile’s product… It’s extremely different to anything else on the market,” said Apple’s Chief Compliance Officer, Kyle Andeer.
Spotify also accused Apple of using its App Store to charge unfair rates – something Spotify’s Head of Global Affairs, Horacio Gutierrez, described as an “Apple Tax”.
He also said that Apple directly competed with Spotify with Apple Music, and the in-app charges had made Spotify less competitive.
“They are undercutting us on price,” he said.
He also criticised Apple for having rules that meant they were unable to tell customers that the service was cheaper if it was bought away from the App Store.
Apple said that Spotify had “been incredibly aggressive when it comes to dealing with artists and creators, and driving a hard bargain”.
Mr Andeer said that “less than 1% of Spotify users pay a commission to Apple”.
Match, which owns Tinder, also criticised Apple and Google for the charges it had to pay.
It is a monopoly when a market leader has the power to control how apps work, how much they must cost, and, in many cases, if they can even survive.”
Apple and Google also denied that their app stores were monopolies, claiming that the fees were fair.
Apple and Epic Games, the creators of the iconic game Fortnite, will begin a legal battle over App Store charges on May 3rd.