ArcGIS Pro 2.8 API Reference Guide
ToJson Method (SpatialReference)
Example 

ArcGIS.Core.Geometry Namespace > SpatialReference Class : ToJson Method
Converts this spatial reference instance into an ArcGIS JSON spatial reference representation.
Syntax
public string ToJson()
Public Function ToJson() As String

Return Value

Spatial reference represented as a JSON string.
Example
SpatialReference srWithVertical = SpatialReferenceBuilder.CreateSpatialReference(4326, 6916);

string xml = srWithVertical.ToXML();
SpatialReference importedSR = SpatialReferenceBuilder.FromXML(xml);
// importedSR.Wkid = 4326
// importedSR.VcsWkid = 6916

string json = srWithVertical.ToJson();
importedSR = SpatialReferenceBuilder.FromJson(json);
// importedSR.Wkid = 4326
// importedSR.VcsWkid = 6916
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

SpatialReference Class
SpatialReference Members