addon-development

Addon Development in Godot 4.3+

Editor plugins extend the Godot editor itself: custom node types, inspector panels, dock widgets, 3D gizmos, and toolbar buttons. All examples target Godot 4.3+ with no deprecated APIs.

Related skills: resource-pattern for custom Resource editors, godot-ui for editor panel UI, csharp-godot for C# plugin development.

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1. Plugin Structure

Every plugin lives inside addons/ at the project root. Godot discovers plugins by scanning for plugin.cfg files.

res://
└── addons/
    └── my_plugin/
        ├── plugin.cfg          # required — plugin metadata
        ├── plugin.gd           # main EditorPlugin script (named in plugin.cfg)
        ├── my_inspector.gd     # optional — EditorInspectorPlugin
        ├── my_dock.tscn        # optional — dock panel scene
        └── icons/
            └── my_node.svg     # optional — custom node icons

plugin.cfg is a plain INI file. Godot reads it when scanning addons/. The script key must point to the main plugin script relative to the plugin folder.

Enable the plugin: Project → Project Settings → Plugins → tick the checkbox next to your plugin name.

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2. @tool Annotation

@tool makes a GDScript (or its C# equivalent) run inside the editor process as well as at runtime. Without it, the script only runs when the game is playing.

GDScript

@tool
extends Sprite2D

# Engine.is_editor_hint() is true when running inside the editor,
# false during a running game. Use it to guard editor-only logic.
func _process(delta: float) -> void:
    if Engine.is_editor_hint():
        # This block runs in the editor viewport — safe to call editor APIs.
        update_configuration_warnings()
    else:
        # Normal game logic here.
        pass


# _get_configuration_warnings() returns an array of strings shown as
# yellow warning icons on the node in the Scene panel.
func _get_configuration_warnings() -> PackedStringArray:
    var warnings := PackedStringArray()
    if texture == null:
        warnings.append("Texture is not set. Assign a Texture2D in the Inspector.")
    return warnings