Top 20 NuGet synchronization Packages

Firebase Web Client
Contains concepts that are used in synchronization tasks.
A lightweight .NET library for keeping an entity and its key synchronized.
Adds setup authoring to your MSI that installs the Microsoft.VisualStudio.Threading assembly to Visual Studio 2010-2012.
Portkit.Time is a library for network time synchronization between computer systems. It supports synchronization over NTP as well as HTTP protocols.
Represents a single threading synchronization.
.NET async/await friendly task synchronization primitives
CSP channels library
.NET Portable Class Library that provides awaitable synchronization primitives for use with code employing the Task abstraction for modeling asynchronous operations.
In-process .NET Standard implementation of an awaitable semaphore.
Asynchronous and synchronous lock with two priorities in C#
This package contains a library of upcastable lists/list wrappers that implement the observable pattern, invoking events when a list is modified, and a set of list bindings that synchronize the content of observable lists using a mapping between item types.
Mutex variable synchronisation
BlitzCache is a thread safe cache that accepts synchronous and asyncronous calls being simplicity its main goal.