ComfyUI Custom Node Development Guide

This skill teaches you how to build modern (V3 Schema) custom nodes and frontend JavaScript extensions for ComfyUI. Always prefer V3 patterns over legacy V1 unless maintaining existing code.

1. The Modern V3 Python Schema

Use comfy_api.latest for all new nodes. The V3 API uses object-oriented definitions with io.ComfyNode, io.Schema, and io.NodeOutput.

Basic Node Anatomy

from comfy_api.latest import ComfyExtension, io, ui

class MyCustomNode(io.ComfyNode):
    @classmethod
    def define_schema(cls) -> io.Schema:
        return io.Schema(
            node_id="MyPrefix_MyCustomNode",
            display_name="My Custom Node",