With the release of Dynamics 365 Customer Engagement 9.0 (July 2017 Update) the old downloadable SDK has been replaced by online documentation and NuGet packages. This means that we can pull the latest SDK assemblies directly from Nuget. Typically you would want the package Microsoft.CrmSdk.CoreAssemblies. You typically download the SDK assemblies directly from the NuGet Package Manager within Visual Studio and then the tools like PluginRegistration via Powershell.
SDK Old World vs. New World
Initially it may feel a little frustrating because instead of having the SDK help file, code samples, plugin registration tool and the rest in one ZIP file you will now have to familiarize yourself with the new online locations and of course will need an Online connection to browse for help. This is assuming you are working on v9+ either online or on premise. If working on an older implementation of course we still have the original SDK’s targeted at those specific versions.
Dynamics 365 SDK Assemblies
Not going to list them all but essentially you will typically grab these from within Visual Studio directly through Nuget Package Manager. If you wish to automate updates and pull these as part of your build process you will need to develop your own powershell script to do it. The SDK assemblies are listed here with release notes.
You can grab them here. .
There are plenty of examples in the main online help file but you can also download the SDK code samples via NuGet too.
Web API – Server Side
Web API – Client Side
As with any NuGet approach there is always the challenge of ensuring that developers are all using the same and latest versions. The update process is typically manual. The way around this is to automate via powershell to pull the latest packages as part of your DevOps Build pipeline.