You don't need an Apple developer account for Swift on server, Windows and Linux.
You need one only to ship apps on Apple platforms, but that's unrelated to Swift. It applies also to apps written in Objective-C, C/C++, and multi-platform language/frameworks like Dart/Flutter.
You need one only to ship apps on Apple platforms, but that's unrelated to Swift. It applies also to apps written in Objective-C, C/C++, and multi-platform language/frameworks like Dart/Flutter.