Authoring & Publishing ComfyUI Custom Nodes

This skill covers writing a ComfyUI custom node pack and publishing it to the Comfy Registry (registry.comfy.org), the public catalog that powers ComfyUI-Manager. For using existing nodes in workflows, see the comfyui-core skill instead.

Minimal Node Pack Structure

A node pack is a Python package placed under ComfyUI/custom_nodes/<name>/. The package __init__.py must export NODE_CLASS_MAPPINGS and NODE_DISPLAY_NAME_MAPPINGS; WEB_DIRECTORY is optional (only if the pack ships frontend JS).

ComfyUI/custom_nodes/my-node-pack/
├── __init__.py          # exports the mappings ComfyUI scans for
├── nodes.py             # node class definitions
├── pyproject.toml       # registry metadata (required to publish)
├── requirements.txt     # optional Python deps
├── .comfyignore         # optional — exclude files from the published archive
├── LICENSE
├── README.md
└── web/js/              # optional frontend extension (see WEB_DIRECTORY)

__init__.py

from .nodes import NODE_CLASS_MAPPINGS, NODE_DISPLAY_NAME_MAPPINGS

# Optional: serve frontend JS/CSS from this folder (path relative to __init__.py)
WEB_DIRECTORY = "./web/js"

__all__ = ["NODE_CLASS_MAPPINGS", "NODE_DISPLAY_NAME_MAPPINGS", "WEB_DIRECTORY"]

A minimal node class (nodes.py)

class ImageSelector:
    CATEGORY = "example"          # menu path where the node appears

    @classmethod
    def INPUT_TYPES(cls):
        return {
            "required": {
                "images": ("IMAGE",),
                "mode": (["brightest", "reddest", "greenest", "bluest"],),
            },
            "optional": {
                "threshold": ("FLOAT", {"default": 0.5, "min": 0.0, "max": 1.0, "step": 0.01}),
                "count": ("INT", {"default": 1, "min": 1, "max": 64}),
                "label": ("STRING", {"default": "", "multiline": False}),
            },
        }

    RETURN_TYPES = ("IMAGE",)        # tuple of output data types
    RETURN_NAMES = ("image",)        # optional friendly output names
    FUNCTION = "choose_image"        # name of the method ComfyUI calls
    OUTPUT_NODE = False              # True for terminal nodes (e.g. SaveImage)

    def choose_image(self, images, mode, threshold=0.5, count=1, label=""):
        import torch
        brightness = [torch.mean(img.flatten()).item() for img in images]
        best = brightness.index(max(brightness))
        return (images[best].unsqueeze(0),)   # MUST return a tuple


NODE_CLASS_MAPPINGS = {
    "ImageSelector": ImageSelector,        # globally unique class_type key
}

NODE_DISPLAY_NAME_MAPPINGS = {
    "ImageSelector": "Image Selector",     # label shown in the UI
}

Node class contract

Member	Required	Purpose
INPUT_TYPES	yes	@classmethod returning {"required": {...}, "optional": {...}}. Each input is (TYPE,) or (TYPE, {opts}).
RETURN_TYPES	yes	Tuple of output type strings (e.g. ("IMAGE", "MASK")). Single output still needs a trailing comma.
FUNCTION	yes	String name of the method to execute.
CATEGORY	yes	Menu path string for the Add Node menu.
RETURN_NAMES	no	Friendly names for outputs (defaults to lowercased types).
OUTPUT_NODE	no	True marks a terminal node that produces a result (save/preview).

The options dict drives the UI widget for each input type:

• ("INT", {"default": 0, "min": 0, "max": 100, "step": 1})
• ("FLOAT", {"default": 1.0, "min": 0.0, "max": 10.0, "step": 0.1})
• ("STRING", {"default": "", "multiline": True})
• (["a", "b", "c"],), a literal list, becomes a dropdown
• ("IMAGE",), ("LATENT",), ("MODEL",) etc. are typed connections (no widget)

The executing method must return a tuple matching RETURN_TYPES, even for a single output (return (result,)).

pyproject.toml — Registry Metadata

Required to publish. comfy node init scaffolds this file. See references/pyproject.toml for a fully-commented example.

[project]
name = "my-node-pack"                          # unique & IMMUTABLE; lowercase, <100 chars, no "ComfyUI" prefix
description = "What this node pack does"
version = "1.0.0"                              # semantic version X.Y.Z — bump to publish a new version
license = { file = "LICENSE" }                 # or { text = "MIT License" }
requires-python = ">=3.10"
dependencies = [
    "comfyui-frontend-package<=1.21.6",        # optional — pin frontend if you ship UI
]
classifiers = [
    "Operating System :: OS Independent",
]

[project.urls]
Repository = "https://github.com/you/my-node-pack"   # REQUIRED — must be a valid repo URL
Documentation = "https://github.com/you/my-node-pack/wiki"
"Bug Tracker" = "https://github.com/you/my-node-pack/issues"

[tool.comfy]
PublisherId = "your-publisher-id"              # the id after @ on your registry profile
DisplayName = "My Node Pack"                   # human-friendly name in the registry
Icon = "https://raw.githubusercontent.com/you/my-node-pack/main/icon.png"   # square, max 400x400px
requires-comfyui = ">=1.0.0"                   # optional ComfyUI version constraint

Field rules (verified against the live spec)

Field	Section	Notes
name	[project]	Unique and immutable once published. <100 chars; alphanumeric + - _ .; no consecutive special chars; can't start with a number/special char; case-insensitive. Don't prefix with "ComfyUI".
version	[project]	Semantic X.Y.Z — X breaking, Y backwards-compatible feature, Z bug fix. Each value is published once and is immutable.
description	[project]	Short summary (recommended).
license	[project]	{ file = "LICENSE" } or { text = "MIT License" }.
requires-python	[project]	e.g. ">=3.10" (recommended).
dependencies	[project]	PEP 508 requirement strings; can pin comfyui-frontend-package.
Repository	[project.urls]	Required — valid GitHub repo URL.
PublisherId	[tool.comfy]	Required — your publisher id (after the @ on your profile).
DisplayName	[tool.comfy]	Friendly registry name (optional).
Icon	[tool.comfy]	URL to a square image, max 400×400px; SVG/PNG/JPG/GIF.
Banner	[tool.comfy]	URL to a 21:9 banner image; SVG/PNG/JPG/GIF (optional).
requires-comfyui	[tool.comfy]	ComfyUI version range using < > <= >= ~= != (optional).
includes	[tool.comfy]	Array forcing extra folders into the published archive.

Controlling the published archive

• .comfyignore uses .gitignore syntax; files listed are excluded from the published archive. Use it to drop tests, examples, large assets, and dev files.
• [tool.comfy].includes is the inverse: it force-includes folders that would otherwise be skipped (e.g. a bundled web/dist).

Registry Setup (one-time)

1. Go to registry.comfy.org and create a publisher.
2. Your Publisher ID is the value after the @ on your profile page. It is globally unique and cannot be changed. Use it for PublisherId in pyproject.toml.
3. In the publisher's section, create an API key. Name it and save it somewhere safe. If you lose it you must create a new one; it is not recoverable.

CLI Publishing Flow

Install comfy-cli (requires Python 3.10+; a virtualenv is recommended):

pip install comfy-cli

Command	What it does
comfy node init	Scaffolds pyproject.toml with registry metadata in the current node pack folder. Fill in the required fields (esp. PublisherId and Repository).
comfy node publish	Validates and uploads the current version to the registry. Prompts for your API key. Prints the registry URL on success.

Versions are immutable. Once a version is published it cannot be modified or overwritten. To ship changes, bump version and publish again. To pull a bad version, deprecate it on the website (More Actions > Deprecate), which prompts users to upgrade rather than deleting it.

CI Publishing (GitHub Actions)

Automate publishing on every version bump. Add the API key as a repo secret named REGISTRY_ACCESS_TOKEN (Settings > Secrets and variables > Actions), then create .github/workflows/publish_action.yml:

name: Publish to Comfy registry
on:
  workflow_dispatch:
  push:
    branches:
      - main
    paths:
      - "pyproject.toml"

jobs:
  publish-node:
    name: Publish Custom Node to registry
    runs-on: ubuntu-latest
    steps:
      - name: Check out code
        uses: actions/checkout@v4
      - name: Publish Custom Node
        uses: Comfy-Org/publish-node-action@main
        with:
          personal_access_token: ${{ secrets.REGISTRY_ACCESS_TOKEN }}

• Triggers on push to main but only when pyproject.toml changes (i.e. when you bump version). workflow_dispatch allows manual runs.
• If your default branch isn't main, update the branches: list.
• The action reads the version from pyproject.toml and publishes it, so the typical flow is bump version, commit, push to main, done.

Optional Frontend Extension

If your pack adds custom UI (widgets, sidebar tabs, menu items), set WEB_DIRECTORY in __init__.py and ship JS there. New frontend extensions should target the modern @comfyorg/extension-api rather than poking at legacy globals; pull in @comfyorg/comfyui-frontend-types for TypeScript types (npm install -D @comfyorg/comfyui-frontend-types). For the full frontend authoring workflow (defineExtension/defineNode/defineWidget and the defineSidebarTab/defineCommand/defineSetting shell APIs), see the sibling comfyui-frontend-extensions skill.

Common Mistakes

1. Forgetting the return tuple. The FUNCTION method must return (value,), not return value, even for one output.
2. Single-element RETURN_TYPES without a comma. ("IMAGE") is a string, not a tuple. Write ("IMAGE",).
3. INPUT_TYPES not a @classmethod. ComfyUI calls it on the class; missing the decorator breaks node loading.
4. Trying to overwrite a published version. Versions are immutable. Bump version instead; deprecate bad ones on the website.
5. Renaming name after publishing. It's immutable and globally unique. Pick a good name (no "ComfyUI" prefix) up front.
6. Missing [project.urls].Repository. It's required; publishing fails without a valid repo URL.
7. Wrong PublisherId. Use the id after the @ on your profile, not your display name.
8. Oversized icon. Must be square and ≤ 400×400px; larger images are rejected.
9. Renaming class keys in NODE_CLASS_MAPPINGS. The key is the class_type stored in workflow JSON. Changing it breaks every saved workflow that used the node.
10. Committing the API key. Store it as the REGISTRY_ACCESS_TOKEN secret; never in pyproject.toml or the repo.

Sources

• Official: Comfy Registry at https://registry.comfy.org and comfy-cli publishing docs used by comfy node publish.
• Empirical: field-rule notes verified against the live spec; common-mistakes list is from observed publish failures.