As announced earlier today, Microsoft has now released Windows 10 SDK and Developer tools. Developers can use these tools to develop Windows 10 apps and submit it to the Store.
Use a free, full-featured Visual Studio Community 2015 client that already includes the Windows 10 developer tools to get started creating innovative and compelling Universal Windows apps and Classic Windows applications. These tools include universal app templates, a code editor, a powerful debugger, Windows Mobile emulators, rich language support, and more, all ready to use in production. Includes the Windows Standalone SDK and mobile emulators.
If you are using a different development environment than Visual Studio 2015, you can download a standalone Windows SDK for Windows 10 installer. Note that you don’t need to install this SDK if you’re using Visual Studio 2015 – it’s already included.