I want to create and edit JSON settings files.

JSON (JavaScript Object Notation) files are used to configure device settings.
JSON is an open standard that allows you to specify your own settings using a JSON editor, without having to understand PCL or PJL commands.
Any JSON-supported text editor can be used to create and edit settings files.

The example below shows how to create and edit JSON files using an online JSON editor.

Go to the Downloads page on the Brother support website to download the Mass Deployment Tool (Windows only).
Extract the downloaded file into the folder you want.
Prepare the JSON schema file containing all the configurable elements for Brother devices. Available schema files are located in the Mass Deployment Tool's schema folder on your computer.

NOTE:

Before you proceed, make sure you have the correct schema file for your model. For a list of available schema files and applicable models, see the README.TXT file in the schema folder.
In your web browser, go to http://www.jeremydorn.com/json-editor/.
Open the Brother JSON schema file in a text editor file and copy and paste its contents into the Schema field on the web page.
Click the Update Schema button.
The attributes section appears at the top of the page.
Scroll down to the settings section, and select "object" from the general drop-down list.
The General settings options appear.
Select "object" from the contact_and_location drop-down list.
Type the contact and location details you want.
Scroll up to the JSON Output area at the top of the page, and then click the Update Form button.
The updated code appears in the preview field.
Copy the JSON output, paste it into the text editor, and save it as JSON file (*.json).