Apple is opening up web distribution for iOS apps targeting users in the European Union starting Tuesday. Developers who opt in — and who meet Apple’s criteria, including app notarization requirements — will be able to offer iPhone apps for direct download to EU users from their own websites.

It’s a massive change for a mobile ecosystem that otherwise bars so-called “sideloading.” Apple’s walled garden stance has enabled it to funnel essentially all iOS developer revenue through its own App Store in the past. But, in the EU, that moat is being dismantled as a result of new regulations that apply to the App Store and which the iPhone maker has been expected to comply with since early last month.