ComfyUI Extension: Workflow to API Converter Endpoint

Authored by SethRobinson

Created

Updated

4 stars

Adds a global /workflow/convert API endpoint to convert non-API workflow formats to API format for ComfyUI execution

Custom Nodes (0)

    README

    ComfyUI Workflow Converter Endpoint

    Version: 2.0 (Custom Node)

    Overview

    A ComfyUI custom node that adds a /workflow/convert endpoint to convert non-API workflow formats to API format. The "Save (API)" client-end Javascript logic has been converted to python so it can run server-side.

    Features

    • Converts non-API workflows to the exact format produced by ComfyUI's "Save (API)" function
    • Uses ComfyUI's actual node registry for accurate conversion
    • Properly handles both list and dictionary widget value formats
    • Preserves Unicode characters (Chinese, Japanese, emojis, etc.) correctly
    • Returns just the node definitions (no wrapper), ready for the /prompt endpoint, same as the original Export (API) option

    Disclaimer

    How robust is this? It handled all my workflows perfectly (even large 200 KB ones using Flux, Wan 2.2, etc) but your results may vary, no promises. It has not been hardened or tested widely, so I don't recommend using this in any public-facing way.

    For example, there is no protection against someone trying to upload a 10 GB file, I don't know what would happen. So I recommend only using this privately (same computer or private LAN) and for non-mission-critical stuff.

    -Seth

    Installation

    Method 1: Git Clone (Recommended)

    cd ComfyUI/custom_nodes
git clone https://github.com/SethRobinson/comfyui-workflow-to-api-converter-endpoint

    Method 2: Manual Installation

    1. Download this repository as a ZIP file
    2. Extract the folder to ComfyUI/custom_nodes/
    3. Rename the folder to comfyui-workflow-to-api-converter-endpoint (remove any -main suffix)

    After Installation

    Restart ComfyUI and the /workflow/convert endpoint will be automatically available.

    Usage

    The endpoint is automatically available after installation. No workflow changes needed - this isn't a node you put in a workflow.

    Send a POST request to /workflow/convert with a non-API workflow JSON (for example, one you exported from ComfyUI using "Save" not "Save (API)") to get back the API format:

    import json
import requests

# Load a non-API workflow JSON from disk
with open("workflow.json", "r", encoding="utf-8") as f:
    workflow = json.load(f)

# Convert to API format
response = requests.post("http://localhost:8188/workflow/convert", json=workflow)
response.raise_for_status()
api_format = response.json()

# Optionally modify parameters in api_format here (e.g., seed, model, etc.)

# Execute the API-format workflow
execute_response = requests.post("http://localhost:8188/prompt", json={"prompt": api_format})
execute_response.raise_for_status()

    Using curl

    • Convert a non-API workflow.json to API format and save as api_workflow.json (bash/zsh):
    curl -s -X POST "http://localhost:8188/workflow/convert" \
  -H "Content-Type: application/json" \
  --data-binary @workflow.json > api_workflow.json

    FAQ

    Why is this needed?

    Ok, here's the deal, you export your workflow, and from your own custom app you call ComfyUI's prompt endpoint to execute it. Well, joke's on you because it gets an error. Why? You can't run workflows directly, you need to choose "Export (API)" which is an option you'll only see if you've enabled developer mode for some reason.

    So you think, cool, I'll just use that. Well, it works, but later you decide you need to edit your workflow a bit and you drag and drop your "API" version into ComfyUI and low and behold, it's a skeleton of a real workflow, it's missing stuff! You you better hope you saved a copy of the ORIGINAL full workflow.

    So this solution allows you to only work with "full workflows", you just have your app do the extra step of converting the workflow to an "API" version before using it. In my app, I check filedates and cache it out.

    The result? I no longer have to manually save two versions of my workflows to use with the API, just the "full".

    How does this work as a custom node?

    Update (v2.0): It turns out you CAN add global endpoints with custom nodes. ComfyUI allows custom nodes to register new HTTP API routes when they are loaded using PromptServer.instance.routes. This custom node registers the /workflow/convert endpoint on startup, so it's available globally without needing to add any node to your workflow. The included placeholder node is just for visibility in the UI but isn't required for the endpoint to function. (thanks onzag for pointing this out)

    Credits

    Created by Seth A. Robinson

    This project was developed with assistance from AI tools for code generation and documentation.