Top 20 NuGet json Packages

Microsoft.Extensions.Configuration (appsettings.json) support for Serilog.
Easy-to-use typesafe REST API client library, which is simple and customisable.
.NET's fastest JSON, JSV and CSV Text Serializers. Fast, Light, Resilient. Contains ServiceStack's high-performance text-processing powers, for more info see: https://servicestack.net/text
NEST 6.x uses an internalized Json.NET serializer. This package enables serialization using your own custom Json.NET serializer
Lightweight and implementation-free interfaces for DTO's, providers and adapters.
A fluent, portable, testable HTTP client library.
Monadic JSON serialization/deserialization library for F#
ASP.NET Core support for JSON PATCH.
ASP.NET Core MVC formatters for JSON input and output and for JSON PATCH input using Json.NET.
A simple library for working with JSON.
The Couchbase authored new and improved client for .NET based languages! Package supports both .NET Core and Full Frameworks 4.5 and greater.
Jwt.Net, a JWT (JSON Web Token) implementation for .NET
App Metrics Formatters for health check results to JSON using Newtonsoft.Json.
This is the Flurl.Http package, repackaged with strongly named assemblies. See http://tmenier.github.io/Flurl for the official project.
Chilkat .NET Core Class Library
WampSharp Newtonsoft.Json support
JSON Schema reader, generator and validator for .NET
C# Library
Extensions to VelocityDB for efficient LINQ index/BTree queries, AzureSession file API usage with Microsoft Azure, import/export to/from CSV and JSON, Sync, GeoHash, Compressed Bitmap and RTree.
Type-safe, easy and power configuration framework for .NET developers