CreateCkptNames ♾️Mixlab

The README says exactly what this node is for: "use CkptNames to compare the effects of different models," with an example workflow (ckpts-image-workflow.json) shipped alongside it. Type a handful of checkpoint filenames into one box, and this node hands them out as a list your graph can iterate over - one full run per checkpoint, same prompt and seed, so you can eyeball how five different models handle the identical generation without manually swapping the loader five times. It sits in the pack's "Experiment" category for exactly that reason: it's a testing tool, not a production node.

How it works

It leans on ComfyUI's native list-execution model. Any node downstream of a list output re-runs once per item in that list rather than once total - so a list of checkpoint names feeding a checkpoint-list-aware loader queues a full generation pass per name automatically, no manual re-running required.

The inputs and outputs that matter

There's really one field: ckpt_names (STRING, multiline, default empty, required) - type your checkpoint filenames here, presumably one per line based on how the pack's example workflow uses it.

The single output is ckpt_names, typed loosely (*) rather than as a strict STRING, and marked as a list. That loose typing is deliberate - it lets the output slot into whatever downstream loader node expects checkpoint names without ComfyUI's type-checker rejecting the connection.

How to install it

Ships with the Mixlab pack.

• ComfyUI Manager: search comfyui-mixlab-nodes, install, restart.
• Manual: cd ComfyUI/custom_nodes && git clone https://github.com/shadowcz007/comfyui-mixlab-nodes.git, install requirements (install.bat on Windows, or ../../../python_embeded/python.exe -s -m pip install -r requirements.txt), restart.

No models to download for this node - it just emits text.

Common issues & troubleshooting

Only the first checkpoint seems to run. The downstream node has to actually be wired for list execution, not just a normal single-value checkpoint loader - a plain dropdown loader will just take the first item and stop. If you're not sure how the wiring should look, pull up the README's ckpts-image-workflow.json example and copy the pattern.

A checkpoint "fails to load." The names have to match your models/checkpoints filenames exactly, typos and extensions included. This node doesn't validate against your actual model folder - it's just a text list - so a mismatched name only surfaces as an error once the loader tries to use it.

Queue takes way longer than expected. That's the point, but worth remembering: each name in the list means a full separate run through your whole graph, not a cheap comparison. Five checkpoints means five complete generations, GPU time and all.