Install Converters via OpenUPM

Unity Package Manager, or UPM for short, is Unity's new solution for managing packages so they don't need to be included inside the /Assets folder.

Have a look at the Unity Package Manager docs for more info.

OpenUPM is wonderful initiative by @favoyang that takes this one step further by providing a unified registry and command-line tool for distributing various packages supporting UPM deployment.

Prerequisites

1. Requires Unity Editor 2018.1 or above, as UPM was first shipped with 2018.1.

2. You already have installed Newtonsoft.Json installed to your Unity project.

   You may visit the any of the "Getting started > Install Newtonsoft.Json-for-Unity" wiki pages to install that beforehand.

3. OpenUPM-CLI

Installing the package (Cloudsmith registry)

Run the following on the command line:

openupm --registry https://npm.cloudsmith.io/jillejr/newtonsoft-json-for-unity/ add jillejr.newtonsoft.json-for-unity.converters

Installing the package (OpenUPM registry)

Run the following on the command line:

openupm add jillejr.newtonsoft.json-for-unity.converters

Updating the package

Updating the UPM package, even if installed via OpenUPM, is identical to the instructions found in the wiki page Installation via UPM - Updating the package.