Kling Master v2.0 Video Generation (fal)

Kling is one of the heavyweights of hosted video generation, and "Master" is its premium tier - the one you pick when you want the model's best motion quality rather than its cheapest. This node wires that endpoint into ComfyUI and, usefully, works two ways: leave the image input empty for pure text-to-video, or plug an image in for image-to-video. Same node, both jobs.

What it actually does

Nothing runs on your machine. Your prompt (and optional image) go to fal.ai, fal runs Kling Master, and you get a clip back - no VRAM, no downloads, billed per generation. Kling's reputation is built on physically believable, smooth motion, and the Master tier is where that shows most. It's a premium option, priced accordingly, so it's the tier for hero shots rather than bulk iteration.

The inputs that matter

• prompt (required): describe the scene, the action, the camera move. Cinematic, plain-language direction lands best.
• duration: 5 or 10 seconds. Ten roughly doubles the cost.
• aspect_ratio: 16:9, 9:16, or 1:1 - widescreen, vertical, or square.
• image (optional): supply one to run image-to-video (animate this still); leave it empty for text-to-video (generate from the prompt alone).

That's the whole surface, which is the nice thing about a hosted model - there's no sampler, CFG, or step count to tune, because all of that lives on fal's side. The output is a single STRING: the video URL, not a playable clip in the graph. Wire it into the pack's Fal Save Media from URL node to download the file to your output/ folder.

Installing it

Fastest: ComfyUI Manager → search ComfyUI-fal-API → install → restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/gokayfem/ComfyUI-fal-API.git
cd ComfyUI-fal-API
pip install -r requirements.txt

Restart ComfyUI. No model file goes in models/; the dependencies are fal-client and a fal API key. Copy config.ini.example to config.ini in the pack folder and set the key under [API], or export FAL_KEY first. No key, no video.

Where people get burned

The Master tier is priced at the top of Kling's range, so the biggest "gotcha" is just the bill - 10-second clips add up quickly, and this isn't the node to hammer for a hundred rough drafts. Use a cheaper endpoint (like the Pro tier) for exploration and switch to Master for the final pass. Identical re-runs come free from the pack's cache, but any changed input bills again.

If a run errors, read fal's message - content-policy refusals on people and likenesses are the common cause, and the pack passes the real text through. And if you're on ComfyUI Windows Portable and hit an import error, install the client into the embedded interpreter: .\python_embeded\python.exe -m pip install fal-client.