A big part of contributing to Terasology comprises of asset creation and modification. Assets in Terasology are just JSON hierarchy files, often bundled with images. Thus arises a need for a good, reliable and powerful tool to edit JSON files.

"JSON Editor Online" is one such powerful editor. The editor window consists of two panes: a source code pane, and a tree view. The tree view displays the JSON code as a hierarchical view. The file itself can be edited from both editor panes, and changes made to either pane can be transferred easily to the other. The editor is available as a web widget which you can access online here. You can also embed the widget in your own web-page. An added bonus is that the editor is free and open source (the source can be found here), and is under constant development.

Usage

JSON Editor Online is a fairly simplistic, easy to use editor.

• To use the editor, visit this site.
• To open a file, select Open -> From disk (or From URL if it's online). If you want to create a new file altogether, select New.
• You can write JSON code in the editor window as you would in any text editor. To use the tree view, see the sub-section below. To transfer changes made from one editor pane to the other, click the appropriate arrow button.
• You can then save the file either offline (on disk) or online by using the Save dropdown. Files saved online can be shared by sharing a generated link.

The Tree View

The tree view is a convenient way to edit JSON files since it provides a simple, easy-to-understand graphical representation of the JSON hierarchy created. It also allows you to focus on the actual content without worrying about syntax errors. Some basic operations and how they can be performed with the tree editor are given below. For a more complete specification, visit this page.

• Adding a new field: Click on the box button next to he drag area of an existing field to open the options dropdown (See the image below). Select Insert to add a new blank field. If you want to add a certain type of field, click the arrow to the right of Insert and select the type of field you want to add. If you are adding fields to an empty object, there will be no Insert option; instead, there will be an Append option. Note that inserted fields will be created on a new line placed above the line whose options menu is being used to create the field.
• Duplicate a field: Open the options menu of the field you want to duplicate, and click Duplicate. The field will be duplicated onto a new line placed below the field that has been duplicated.
• Remove a field: Open the options menu and click Remove.

A complete beginner's guide can be found here.