UNet Downloader

Drag this node into your graph, hit Queue, and nothing visibly happens. That's not a bug - it's the whole design. UNetDownloader is a stub whose real job is a browser page, and knowing that up front saves you ten minutes of confused staring at a workflow that never completes.

The actual tool lives at http://localhost:8188/unet_downloader (or wherever your ComfyUI server is): a web form that downloads FLUX, SD3, and other UNet/Diffusion files straight into ComfyUI/models/unet/, where the Load Diffusion Model node in your FLUX workflow already expects them. FLUX.1 Dev/Schnell files run 12–24GB (the pack's own page lists the fp8 variants at ~24GB), so this is the kind of download you'd rather not babysit with wget and a prayer for disk space. That's the niche: pull a huge UNet from HuggingFace, Civitai, or a direct link directly into the right folder, from the browser.

Here's the mechanism, since it's the weird part. The node itself has just two required inputs - unet_name (the filename to save, default flux1-dev-fp8.safetensors) and download_url - and no outputs at all. It's an output node that returns immediately. The actual download is a POST to /unet_downloader/download on ComfyUI's internal PromptServer, which streams the file to the unet folder with safe_join so a sneaky filename can't escape that directory. It skips the download entirely if the file already exists. The pack's JavaScript also appends a "UNet 下载器" button to the ComfyUI menu that opens the web UI in a new tab.

The inputs that matter, both plain text:

• unet_name - keep it a bare filename like flux1-dev-fp8.safetensors. It's joined to models/unet/, and subfolder names work too.
• download_url - a direct link to the .safetensors/.ckpt/.pt/.pth file.

The node is optional, honestly. Everything it does, the web page does better, including a list of models you already have and a "download to my browser" button - handy if you're renting a cloud box and want to pull your files back off it.

Install

ComfyUI Manager is the easy route - search "UNet Downloader for ComfyUI" and install. Manual works too:

cd ComfyUI/custom_nodes
git clone https://github.com/huihuihuiz/unet_downloader

Then restart ComfyUI. Good news: its only Python dependency is requests, already everywhere. No compile step, no version hell - this is the rare custom node that won't fight your environment.

Where people get burned

• No resume support. It streams via a plain requests.get with no Range handling, so a dropped connection on a 24GB download starts over from zero. Use a stable connection, or do the big ones yourself with wget -c and let this handle the small stuff.
• No auth headers. There's no field for a HuggingFace token or Civitai API key, so gated repos or signed-only URLs will 403. Use direct, signed, or public links.
• "Already exists" is a feature. If the file name matches something in models/unet/, it reports it already exists and moves on. You didn't break it.
• The UI is Chinese-language. The menu button reads "UNet 下载器", the form says "下载 UNet 模型". The fields are obvious enough, but don't panic when you don't see English.

Is it essential? No - you can download files by hand faster than this pack installs. But for a FLUX setup with 20GB of models to land in the right folder, and especially on a remote box where "download to local" saves you, it's a reasonable quality-of-life add. Just don't expect the graph node to do anything; the web page is the product.