Used Upgrade WP for Windows 10 for Windows?
The Download Now link directs you to the Windows Store, where you can continue the download process. You must have an active Microsoft account to download the application. This download may not be available in some countries.
Developer’s Description
By Desert fish
This app can help you to upgrade to the Developer preview version.
Developer preview version is for developers, so ordinary users if you want to experience the Windows Phone's latest preview version first need to turn himself into a developer, is also say their Microsoft account into a developer account.
Used Upgrade WP for Windows 10 for Windows?
