😃 SML Flux Pro 1.1 (Replicate)

The name is a small lie. "SML Flux Pro 1.1" sounds like a checkpoint you load, but this node never runs any model on your machine - it's a wrapper that phones FLUX.1 [pro] on Replicate and hands you back the finished image. That's the whole point. Pro is the API-only tier of the Flux family, the one Black Forest Labs never released as weights, and this is the easiest way to get its output into a normal ComfyUI graph without downloading a single checkpoint.

Why would you bother? Two reasons. First, Flux Pro was the benchmark the open-source community measured itself against after Flux closed the gap with Midjourney - if you want that specific model's look, you can't run it locally, period. Second, your GPU doesn't matter here. No 12B stack, no T5-XXL, no quantized GGUF juggling; your machine just needs enough RAM to hold the result. The flip side is the thing people keep tripping on: it's still cloud generation, you're paying per image, and you get none of the local-model toys - no LoRAs, no ControlNet, no negative prompt (Pro is guidance-distilled like the rest of the family, so it wouldn't take one anyway).

How it works

Thin wrapper, genuinely. When you hit Queue, the node assembles your prompt and a handful of parameters, calls black-forest-labs/flux-1.1-pro through Replicate's Python client, waits for the run to finish, downloads the PNG it returns, and decodes it into a normal float IMAGE tensor. The replicate==1.0.4 dependency is pinned in requirements.txt; the only real config is an API key sitting in a config.ini file.

The inputs that matter

The schema is honest and mostly flat, but a beginner really touches three things:

• prompt (multiline) - write full sentences, not tag soup; Flux's T5 encoder rewards natural language.
• aspect_ratio - ten presets from 1:1 through 9:16. Pick custom and the width/height fields (256–1440) take over.
• seed (optional, default -1) - set it to reproduce a result; -1 means random every run.

Worth knowing: guidance defaults to 3 (range 2–5) - the KB's Flux guidance-3.5-is-too-high advice applies less here since Pro ships its own tuned default. steps defaults to 30, and prompt_upsampling (off by default) lets the model expand your short prompt for better detail. Output is a single IMAGE tensor - wire it straight into Save Image or Preview. It's already a raster, so no VAE decode step.

Install

ComfyUI Manager: search the pack title and hit install, then restart. Or by hand:

cd ComfyUI/custom_nodes
git clone https://github.com/smlbiobot/ComfyUI-Flux-Replicate-API
cd ComfyUI-Flux-Replicate-API
pip install -r requirements.txt

Then the step everyone misses. Grab a token at replicate.com/account/api-tokens, and:

cp config.ini.example config.ini
# edit config.ini, set REPLICATE_API_TOKEN = your-key-here

No model downloads, no heavy dependencies - just that key. The pack's own author is a known cloud-workflow community member, and the node is literally the one r/comfyui users point each other to when someone asks how to run Flux 1.1.

Common issues

• You get a solid black 1024×1024 image. That's the node's failure mode, not the model's: any API error gets caught, logged to the console as Error generating image with FluxPro, and swapped for a blank frame so the workflow doesn't crash. Black square = open the ComfyUI console and read the last error. Usual causes: the key isn't in config.ini (which must live inside the pack folder, not your user dir), the account has no billing set up, or Replicate is rate-limiting you.
• It blocks the queue. Each call takes tens of seconds remotely and the node waits synchronously. Batch what you can.
• It costs money per image. This is a convenience for people who want Pro quality without the VRAM, not a free lunch.

Reach for it when you need exactly Flux Pro's output or your card can't hold the 24GB stack. For everything else, a local Dev build plus the upscaler of your choice is cheaper and more controllable.