FalAddLora

FalAddLora doesn't call any API, needs no key, and can't generate anything. It's a LoRA builder - the node that assembles the list of LoRAs you hand to FalFluxLoraAPI. If that sounds anticlimactic, think of it as the JSON equivalent of ComfyUI's LoraLoader stack: you add one per LoRA you want, and the final node in the chain is the one that actually spends money.

The way it works is dead simple. Type a lora_url (the URL of the LoRA file you want fal to load) and a scale, and it outputs a JSON string like {"loras": [{"path": "...", "scale": 1.0}]}. Feed that into FalFluxLoraAPI's loras input. The optional loras input lets you chain nodes - wire one FalAddLora's output into the next one's optional loras, and it appends to the list instead of starting fresh, so you can stack style + character LoRAs the same way you would locally.

The inputs that matter

Only two real knobs:

• lora_url - a URL fal can fetch the LoRA from. CivitAI download links and similar direct-file URLs work; that's the whole field, no file picker here.
• scale - 0.1 to 4.0, default 1.0. The community default of 1.0 is often too strong; 0.5–0.8 is a common sweet spot, same as local Flux LoRA practice.

The optional loras input is the chain point for stacking multiple LoRAs. The single STRING output is what wires into FalFluxLoraAPI. That's the whole node.

Install

It ships with the ComfyUI-Cloud-APIs pack:

cd ComfyUI/custom_nodes
git clone https://github.com/BetaDoggo/ComfyUI-Cloud-APIs

or Manager → search "ComfyUI-Cloud-APIs", then restart. No key needed for this node - the key lives on FalFluxLoraAPI, which is where the money goes.

Troubleshooting

• "loras" shows an error - make sure you're feeding the output of FalAddLora into it, not typing JSON by hand. The optional chaining input only exists so nodes can stack.
• LoRA silently not applied - check the URL is directly downloadable, and bump the scale. A 0.1-scale LoRA on a weak file can be nearly invisible.
• Why not skip the helper? Because the pack's loras field is a STRING with forceInput - it expects exactly this JSON shape. You could hand-craft it, but the helper exists so you don't have to.

Keep in mind the pack is unmaintained. This node is so trivial it'll probably keep working forever, but if fal's LoRA JSON schema ever changes, this is one of the first places you'd need to fork.