N8N Backend

n8n ↔ ComfyUI over raw HTTP is a legendary pain point - there's a 103-upvote r/comfyui thread titled "N8N to ComfyUI seems like a nightmare" from someone who just wanted to trigger a WAN video job from a Google Sheet and drowned in requests syntax. The N8N Backend node is StudioDeep's answer: instead of hand-rolling HTTP, you point a node at your webhook and the pack handles the plumbing.

Like its sibling LLM Backend, this is a config node. You give it a webhook_url, optionally a username/password, and it produces an AI_BACKEND value. But where the LLM Backend routes to Anthropic/OpenAI, this one routes to your n8n workflow - the webhook does whatever you built it to do and returns the answer.

How it works

Under the hood it just packs {type: "n8n", webhook_url, username, password} and passes it on the wire. The real work happens in the downstream nodes, which POST JSON to that URL with basic auth if you supplied credentials, then read the response. Three nodes in the pack can consume it:

• Image Prompt by Seed Idea posts {"seed_idea": ..., "model": ...} and expects {"prompt": "..."} back.
• T2V Prompt Builder posts the whole assembly job (prompt, locked, auto, options, enhance) and expects {"prompt": "..."}.
• Image Analyzer posts {"image_url": ...} and is more tolerant - it looks for output, data, or json_output in whatever JSON you return.

So the actual brains - which LLM, which image model, which data source - live in your n8n workflow, not in ComfyUI. That's the point: you can mix in data from a spreadsheet, a queue, a database, anything n8n touches.

Inputs and output

Only three inputs: webhook_url (defaults to a https://your-n8n-instance.com/webhook/... placeholder - replace it), username, and password. Leave username/password empty if your webhook is unauthenticated; the node only sends an auth header when a username is set. Output is a single backend (AI_BACKEND).

Installing

Same as every StudioDeep node - ComfyUI Manager, search "StudioDeep", install, restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/studiodeep-ai/comfyui-studiodeep StudioDeep
pip install -r StudioDeep/requirements.txt

No models, no .env file, just requests (already a dependency of the pack).

The trap

The default webhook URL is a placeholder - paste a real one. And test the webhook in n8n's own console before wiring it into ComfyUI. If your workflow returns the wrong shape, downstream nodes fail silently: ImagePromptBySeedIdea and T2V Prompt Builder both do response.json().get("prompt", ""), so a missing key gives you an empty string with zero error. Match the JSON contract above and life is easy; guess, and you'll debug for an hour. Also mind the 30-second timeout on the prompt nodes - if your n8n workflow chains multiple LLM calls, keep it fast or the request dies mid-thought.