Create your own node based editors that work both in editor window and exported in builds by writing standard GUI/GUILayout interface.

Check the [WebGL demo]

Features:

• Menu
• Selecting
• Dragging
• Panning
• Deleting
• Connecting
• Deconnecting
• Sizing
• Renaming
• Minimap
• Grid
• Snapping
• Styling
• Popups
• Tooltip
• Runtime
• Serialization
• Full C# source

Feature details and documentation can be found here.