One of the benefits of Azure is that it can be used in Microsoft data centers around the world and developed and tested on premises before deployment using the Microsoft Azure Software Development Kit (SDK). Microsoft Azure is the only cloud vendor that has an SDK to emulate all the pieces in Visual Studio 2012. The SDK allows you to even develop pieces on-site and pieces in the cloud to create hybrid solutions. The Windows Azure SDK from Microsoft is considered open source. Some important links are:
https://github.com/Azure: This is the GitHub open source location
https://github.com/Azure/azure-sdk-tools: This contains Microsoft Azure PowerShell tools
http://research.microsoft.com/en-us/projects/azure/windows-azure-for-linux-and-mac-users.pdf: This provides Azure command-line tools for Linux and Mac operating systems
https://azure.microsoft.com/en-us/: This contains Getting Started tutorials
https://manage.windowsazure.com/: This is the Azure cloud portal