Top 20 NuGet collections Packages

Provides a set of collections that reduce the memory usage and more especially the large object heap.
Package Description
A set helpful extensions for Microsoft.Extensions.DependencyInjection.
An auto-serializing, in memory, optimized, lightweight, persistent database as a drop in to List.
Provides fast and memory efficient alternatives to the collections in System.Collections.Immutable. Currently just includes SchematiqList as a replacement for ImmutableList.
.NET Portable Class Library that provides a very simple implementation of an immutable list of (cons) cells.
Code generator for [FlagsEnumeration]-decorated types. Automatically generates bitwise operator overloads corresponding with your derived Enumeration assets. This package references all required and recommended analyzer packages. See project site for installation instructions and more details.
Contains specialized Dictionary implementations, that are 4x faster than the .NET default Dictionary. Breaking changes in 3.1.x - See https://github.com/Capgemini/Cauldron for more information.
An extended set of collections for .NET Standard
General-purpose library for full-stack use. Provides support for Caching, Collections, Comparers, Converion, Environment, Events, Exceptions, IO, FileSystem, Lambdas, Logging, Math, Memory, Scopes, Text, Threading, Scheduling and many other aspects.
VivaldiSoft.Collections is a cross-platform open-source library which provides data structures utilities to .NET developers
This is a .NET Standard 1.0, Silverlight 5.0 and Windows Phone Silverlight 8.0 & 8.1 backport from System.Collections.Concurrent.ConcurrentDictionary and System.Collections.Concurrent.ConcurrentQueue as defined in .NET Core
Paginable extension with Microsoft EntityFrameworkCore for collection.
Collections and collection extensions
MPSC.PlenoSoft.Core.Collections
Ratchet Octree provides a basic impletation for Octrees in .NET
Defines an IImmutableSet that implements IReadOnlySet.
Various .NET code utilities, collections, unicode, etc.