JSON is becoming more and more the new XML. So similar to XML Schema Definitions(XSD) we see schema definitions pop up for JSON data. One tool that can help you generate a schema definition is JSONschema.net.
From the website:
JsonSchema.net is a tool that automatically generates JSON schema from JSON according to the IETF JSON Schema Internet Draft Version 4. JSON Schema will be automatically generated in three formats: editable, code view, and string.
Using this tool, you provide a valid JSON object, click Generate Schema and done!
The generated schema can be viewed, edited(temporarily disabled) and copied: