Top 20 NuGet immutable Packages

A very lightweight utility library for increased expressiveness.
An immutable, covariant list with eager load semantics.
NitroBolt.Immutable
This library provides F# integration for the Imms immutable collections library.
A short and sweet REST client
A helpful library for including signals into your domain model.
Contains implementation of immutable arrays with special immutable implementation for array operations for saving memory.
Immutable persistent collections, algebraic sum-type aka descriminated union, Ref type and supportive extensions for performant functional programming in C#. Split from the DryIoc: https://github.com/dadhi/DryIoc
T4 templates that transform simple mutable type definitions into fully functional immutable types with persistent characteristics.
The runtime components behind the parts generated by the ImmutableObjectGraph.T4 package.
Package Description
Immutable n-ary relation data structure for .NET Standard 2.0
Defines `[Record]` attribute and `Features` flags enum. See project site for more details.
.NET Standard library for building immutable models
An implementation of IImmutableDictionary<TKey, TValue> that maintains O(1) value lookup, at the cost of mutation performance.
my useful LiteDB extension methods.
Roslyn powered analyzers for C# to support defining immutable types
Alternative or extended collection types for .NET
Semantics used by Apex.Analyzers.Immutable