Top 20 NuGet polymorphism Packages

Discriminated Json Subtypes Converter implementation for .NET
Adds System.Text.Json serializer support for polymorphism with a discriminator attribute.
Discriminated Json Subtypes Converter implementation for .NET
Allows editing blueprints at runtime.
Allows editing blueprints at runtime.
Bind classes to interfaces, enabling more polymorphic inheritence and extensability of code you don't own, or making using legacy code slightly more enjoyable.
Abstraction convertion functionalities and polymorphism for System.Text.Json
A serializer that supports polymorphism, constructor injection, circular references and linking to external documents.
ObjectEnum is a wrapper for enums, adding a certain degree of polymorphism.
RoyalXml is a simple, highly customizable XML serializer for .NET. Though it can be configured in almost any way, the default serialization ruleset supports polymorphism, multidimensional arrays, and collections.