It has cost Epic Games more than $100 million to challenge Apple's App Store rules in the ongoing Apple vs. Epic Games legal battle, Epic

Apple on Monday lodged an appeal to challenge a U.S. judge’s ruling that ordered the tech company to immediately open its lucrative App Store to more competition.

After a stinging rebuke in the lower courts over its legal battle with Epic, Apple filed a notice of appeal to the Ninth Circuit on Monday. The appeal will challenge last week’s ruling that prevents the company from charging developers fees on purchases made outside the App Store.