FL Kartel Job Output

The other half of the Kartel integration pair: where FL_KartelJobInput decodes an inbound job payload at the start of your workflow, FL_KartelJobOutput is the terminal node that ships the result back out - POSTing your generated images to Kartel's callback URL as a multipart request, with the job's identifying metadata attached as JSON.

How it works

It packages your image batch as multipart PNG uploads and sends them, along with a JSON metadata blob (job ID, user ID, email, app name), to whatever callback_url you give it. There's a deliberate safety valve built in: if callback_url is empty, or the image input is just a 1×1 placeholder (the kind of thing you get from an unconnected or aborted branch), the node skips the POST silently instead of firing off a broken or meaningless callback.

The inputs and outputs that matter

Required: images (the batch to send back), job_id, and callback_url.

Optional: user_id, user_email, app_name - extra metadata to include in the POST if your callback consumer needs it.

No outputs - this node has none listed, because it's a terminal output node: its entire purpose is the side effect of the POST request, not producing something for another node to consume.

How to install it

Part of ComfyUI_Fill-Nodes. ComfyUI Manager: search ComfyUI_Fill-Nodes, install, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/filliptm/ComfyUI_Fill-Nodes

then restart. Needs only an HTTP client to POST - no model download.

Common issues & troubleshooting

Silent skip means "nothing happened" can look identical to "it worked." Because a missing callback_url or a 1×1 placeholder image causes this node to quietly do nothing rather than error, a broken upstream wire (an unconnected image socket, a job-input node that failed to populate callback_url) can pass through your whole pipeline without any visible failure - the workflow just "completes" and nothing was ever sent. If results aren't reaching Kartel, check that callback_url and images are actually populated with real values before this node, not just that the workflow ran without errors.

Feed it the same job_id and callback_url that came from FL_KartelJobInput. These need to match the job you're responding to - if you're processing multiple jobs in one session, keep the metadata wired straight through from input to output for a given run rather than reusing values from a previous job.

This node is Kartel-specific plumbing, like its input counterpart. Outside of an actual Kartel integration, there's no reason to reach for this - it's not a general-purpose "POST an image to a webhook" node, it's shaped specifically around Kartel's expected multipart-plus-JSON-metadata contract.

Network failures on the POST itself aren't something this node exposes an output for. Since there's no output socket, if the callback endpoint is down or rejects the request, that failure surfaces in ComfyUI's console/logs rather than as a value you can branch on in the graph - check the logs if Kartel reports it never received a result.