Mirosoft Director of Sales Excellence, Eric Ligman, writes a post about 100s of FREE Microsoft eBooks each year.

These are legal DRM-free copies (PDF/EPUB/MOBI) on various Microsoft technologies like Windows, SQL Server, Azure, SharePoint, PowerShell, Visual Studio, Office, Dynamics etc.

The titles may repeat in multiple links below so I’d suggest that you begin browsing at the latest year URL and go backwards from there.

2017

https://blogs.msdn.microsoft.com/mssmallbiz/2017/07/11/largest-free-microsoft-ebook-giveaway-im-giving-away-millions-of-free-microsoft-ebooks-again-including-windows-10-office-365-office-2016-power-bi-azure-windows-8-1-office-2013-sharepo/

2016

https://blogs.msdn.microsoft.com/mssmallbiz/2016/07/10/free-thats-right-im-giving-away-millions-of-free-microsoft-ebooks-again-including-windows-10-office-365-office-2016-power-bi-azure-windows-8-1-office-2013-sharepoint-2016-sha/

2015

https://blogs.msdn.microsoft.com/mssmallbiz/2015/07/07/im-giving-away-millions-of-free-microsoft-ebooks-again-including-windows-10-windows-8-1-windows-8-windows-7-office-2013-office-365-sharepoint-2013-dynamics-crm-powershell-exchange-se/

2014

https://blogs.msdn.microsoft.com/mssmallbiz/2014/07/07/largest-collection-of-free-microsoft-ebooks-ever-including-windows-8-1-windows-8-windows-7-office-2013-office-365-office-2010-sharepoint-2013-dynamics-crm-powershell-exchange-server-lync-2/

2013

https://blogs.msdn.microsoft.com/mssmallbiz/2013/06/18/huge-collection-of-free-microsoft-ebooks-for-you-including-office-office-365-sharepoint-sql-server-system-center-visual-studio-web-development-windows-windows-azure-and-windows-server/

2012

https://blogs.msdn.microsoft.com/mssmallbiz/2012/07/27/large-collection-of-free-microsoft-ebooks-for-you-including-sharepoint-visual-studio-windows-phone-windows-8-office-365-office-2010-sql-server-2012-azure-and-more/