BytePlus Seedream 4.5 & 5.0

Seedream is one of those models people keep asking whether they can run locally, and the answer has been no every single generation. ByteDance's pattern is ruthless about it: components ship open (PuLID, Depth Anything, SDXL-Lightning, Bernini), products stay on the API - and the Seedream image line is a product. So if you want Seedream in your graph, you call it. This node is that door, and because it's shipped by BytePlus itself rather than as a third-party wrapper, it bills your own BytePlus account at contract/resource-pack pricing instead of burning Comfy credits.

What you're buying, beyond quality, is editing. Seedream is not just a text-to-image generator; it does precise single-sentence edits on a reference image, and this node exposes that as reference-image slots rather than a separate mode.

How it works

One node covers Seedream 5.0 Pro, 5.0 Flash, 5.0 Lite, 4.5 and 4.0, and the differences are real, not cosmetic. Pro and Flash return one image by URL. Lite, 4.5 and 4.0 stream their images inline and can generate a set of related images in one call. Some models have "thinking" (prompt-optimization reasoning), some have a fast prompt-optimization mode, some support transparent background. The picker shows you the fields the chosen model actually accepts, which is why the node looks different depending on what you select.

Prompt and model are the two required inputs. Everything else lives under the model you picked.

The inputs worth setting

• prompt does double duty: describe an image to create it, or describe a change to edit a reference. Editing is the reason to reach for this over a local model - "make the jacket red, keep everything else" is a one-line operation here and a masking session locally.
• size_preset, or width / height when the preset is Custom. Presets cover the usual ratios at each resolution the model supports; 5.0 Pro and Flash add 1.5K priced like 1K on Pro. The custom range runs from 1:16 to 16:1 aspect, so panoramas and verticals are both fine.
• images - up to 10 reference images, 14 on 5.0 Lite. This is the editing and multi-reference path: hand it a character and a product and ask for both in one shot.
• max_images (Lite, 4.5, 4.0 only) generates a related image set - story scenes, character variations - from one prompt. Input plus generated images can't exceed 15. Set fail_on_partial if you'd rather the whole run abort than quietly hand you a short batch.
• seed is a re-run trigger, not determinism. Same for generation_count, the pack's own extra: it fires parallel requests, so it's the batch dial rather than a "more tries" dial.
• watermark adds the AI-generated mark. thinking (5.0 models) turns prompt-optimization reasoning on; the tooltip warns it can substantially increase generation time, notably on 5.0 Pro, and it can only be disabled for text-to-image.
• Transparent background is a Pro/Flash feature: set output_format to png and background to transparent, and connect your reference image's MASK output (from Load Image) to reference_mask. The node's mask output then carries the result's transparency - 1 means transparent, same convention as Load Image.

Outputs are IMAGE, response (request metadata as JSON) and mask.

Install and key

cd ComfyUI/custom_nodes
git clone https://github.com/byteplus-sa/ComfyUI-BytePlus-ModelArk
pip install -r ComfyUI-BytePlus-ModelArk/requirements.txt

Restart (ComfyUI 0.31.0+), or search BytePlus ModelArk in ComfyUI Manager. Save your ModelArk API key and region in Settings → BytePlus (or BYTEPLUS_API_KEY / BYTEPLUS_REGION in user/.env), and activate the model you want in the ModelArk console for that region - 5.0 Lite isn't available in eu-west-1, for instance.

The node saves nothing. Connect a Save Image or nothing lands on disk, and remember a node with no consumer doesn't run at all, so an orphaned Seedream node costs nothing.

Where people get burned

Region/key mismatch is the #1 401 in this pack, and it's the one to check first.

The subtler one: people expect generation_count to be "3 attempts, keep the best." It isn't - it's three parallel billed requests, all returned to you as a batch, and each one costs money. That's the right shape for a lookbook, wrong for a reroll.

And the elephant: this is metered, per call, forever, and your prompt and reference images leave your machine. The r/comfyui reaction to closed models arriving in ComfyUI was loud on exactly that point. If the job is "make 200 images of my OC," a local checkpoint plus a LoRA is the answer. If the job is "edit this product photo on a sentence that includes legible text," this is one of the few tools that does it.