Seedream 5.0 API

At a glance

Pricing

Cost = credits per image × n. Credits are reserved when you submit a job and refunded in full if it fails or you cancel it before it starts.

List prices elsewhere

Publicly listed per-image prices for comparable access to this model, read from each provider's own pricing page. Providers change prices without notice — follow the links for the current figure.

Quick start

Create a key in the dashboard, then submit a job and poll it. Replace the id in the second call with the one the first call returns.

1. Submit a generation

curl -s -X POST https://api.genmux.tech/v1/generations \
  -H "Authorization: Bearer $API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{"model":"seedream-5","prompt":"a red fox in fresh snow, low winter sun","n":1,"resolution":"2K","ratio":"1:1"}'

{
  "id": "0d8b6a3e-2f1c-4a5b-9c1d-7e2f3a4b5c6d",
  "model": "seedream-5",
  "status": "queued",
  "params": {"prompt": "a red fox in fresh snow, low winter sun", "n": 1, "resolution": "2K", "ratio": "1:1"},
  "cost": 16,
  "created_at": "2026-08-30T20:01:12.345Z"
}

2. Poll until status is succeeded (typically 1–20 s)

curl -s https://api.genmux.tech/v1/generations/0d8b6a3e-2f1c-4a5b-9c1d-7e2f3a4b5c6d \
  -H "Authorization: Bearer $API_KEY"

{
  "id": "0d8b6a3e-2f1c-4a5b-9c1d-7e2f3a4b5c6d",
  "model": "seedream-5",
  "status": "succeeded",
  "cost": 16,
  "images": [
    {"index": 0, "url": "https://…/0.png?X-Amz-Expires=900&…", "expires_at": "2026-08-30T20:16:30Z", "mime": "image/png", "width": 1024, "height": 1024, "bytes": 1843201, "sha256": "9f2c…"}
  ],
  "created_at": "2026-08-30T20:01:12.345Z",
  "finished_at": "2026-08-30T20:01:19.802Z"
}

import os, time, uuid, requests

BASE = "https://api.genmux.tech"
auth = {"Authorization": f"Bearer {os.environ['API_KEY']}"}

job = requests.post(
    f"{BASE}/v1/generations",
    headers={**auth, "Idempotency-Key": str(uuid.uuid4())},
    json={"model": "seedream-5", "prompt": "a red fox in fresh snow, low winter sun", "n": 1, "resolution": "2K", "ratio": "1:1"},
    timeout=30,
).json()

while job["status"] in ("queued", "running"):
    time.sleep(1)
    job = requests.get(f"{BASE}/v1/generations/{job['id']}", headers=auth, timeout=30).json()

print(job["images"][0]["url"])  # presigned, valid for 15 minutes

const BASE = "https://api.genmux.tech";
const auth = { Authorization: `Bearer ${process.env.API_KEY}` };

let job = await fetch(`${BASE}/v1/generations`, {
  method: "POST",
  headers: { ...auth, "Idempotency-Key": crypto.randomUUID(), "Content-Type": "application/json" },
  body: JSON.stringify({ model: "seedream-5", prompt: "a red fox in fresh snow, low winter sun", n: 1, resolution: "2K", ratio: "1:1" }),
}).then((r) => r.json());

while (job.status === "queued" || job.status === "running") {
  await new Promise((r) => setTimeout(r, 1000));
  job = await fetch(`${BASE}/v1/generations/${job.id}`, { headers: auth }).then((r) => r.json());
}

console.log(job.images[0].url); // presigned, valid for 15 minutes

Frequently asked questions

What is the Seedream 5.0 API?

Seedream 5.0 is ByteDance's image model from the Seedream line, which the team has built around photoreal output and legible in-image text at high resolution. On Unified Image API the Seedream API is the model id "seedream-5", and it sits at the high-resolution end of this catalogue: it renders at 2K, 4K — there is no 1K tier — takes up to 4 reference images per request, and costs 2K — 16 credits · 4K — 18 credits.

How much does one Seedream 5.0 image cost?

From 16 credits per image, about $0.20 at the Scale pack rate. Price follows the resolution tier: 2K — 16 credits · 4K — 18 credits. A request for n images costs n times the per-image price. Credits are prepaid, so there is no subscription and no per-seat fee.

Why is there no 1K option on Seedream 5.0?

Because the model is only served at 2K, 4K upstream, so those are the only tiers we can quote and bill. The request therefore defaults to 2K when you omit the resolution field, and asking for 1K returns a 400 validation_error rather than a quietly downscaled image. If you need a smaller asset, resize the 2K output on your side, or draft on a model whose spec table lists a 1K tier — most of the catalogue does.

When should I use Seedream instead of Nano Banana Pro?

Both reach high resolution tiers and both take reference images, but Seedream 5.0 is priced well above Nano Banana Pro per image — compare the two pricing tables — so it should earn the difference on the specific frame: a photoreal composition, or one where a line of text has to stay clean at print size. Nano Banana Pro also has a 1K tier for drafts, which this model does not. The practical method is to draft cheaply elsewhere and re-render the keeper here: same key, same body, one field.

What resolutions does Seedream 5.0 support?

Resolution is a tier, not a pixel size: this model renders at 2K, 4K, and the request defaults to 2K when you omit the resolution field. A tier outside that list is rejected with a 400 validation_error rather than quietly downscaled, so you always know which price you are paying. The legacy size field ("1024x1024") still works for existing integrations and is mapped to the nearest tier and ratio.

What aspect ratios can I ask for?

auto, 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, 2:3. Pass it as the ratio field; it defaults to 1:1, and "auto" lets the model choose the shape that fits the prompt. A ratio outside the list is a 400 validation_error. Ratio never changes the price — only the resolution tier does.

Can I send reference images (image-to-image)?

Yes. Pass images as an array of public https URLs — up to 4 per request — and the prompt then describes the edit or the variation rather than the whole scene; with reference images the prompt itself is optional. URLs must be reachable from the public internet: private hosts and non-https URLs are rejected with a 400 validation_error.

Is there a negative prompt?

Yes. Pass negative_prompt alongside prompt to describe what you do not want in the frame — artefacts, text, watermarks, a colour you are steering away from. It costs nothing extra.

How many images can I generate in one request?

Up to 4 per call, via the n field. Each image is billed separately, so n=4 at 2K costs 4 times the per-image price. For larger batches submit several jobs — throughput is bounded by your account's in-flight job limit (20 by default), not by n.

Are generations reproducible? Does it support seeds?

Yes. Pass an integer seed alongside the prompt, and the same seed with the same prompt, resolution and ratio gives you a reproducible result — which is also how you compare two models fairly. Leave it out and each call is sampled independently.

How long does a generation take, and do I have to poll?

Typically 1–20 seconds from submit to succeeded, depending on the resolution tier and queue depth. The API is asynchronous: POST /v1/generations returns a job id in milliseconds, and from there you either poll GET /v1/generations/{id} or pass webhook_url and let us POST you once the job finishes, retrying with backoff for up to 8 attempts until your endpoint returns 2xx. Every delivery carries an HMAC-SHA256 signature you verify with your account webhook secret.

What happens if a generation fails?

You are not charged. Credits are reserved when the job is created and refunded in full if the job fails, is cancelled while still queued, or the model is temporarily unavailable (503 model_unavailable). The failed job carries an error object with a code such as content_policy so you can branch on it.

What stops me from being double-charged on a retry?

Every POST /v1/generations requires an Idempotency-Key header. Resending the same key returns the original job with 200 and charges nothing extra, so a network timeout can be retried safely. Reusing a key with a different body is rejected with 422 idempotency_key_mismatch.

Can I use the generated images commercially?

Yes — under our terms of service you own the rights we can pass on to the output of your generations and may use them commercially, provided the prompt and the use comply with the terms and the upstream model provider's content policy. Read the terms before shipping anything customer-facing.

Other models

Same key, same request shape — switch by changing the model field.

• Nano Banana API

  nanobanana

  Fast, general-purpose text-to-image and image-to-image generation at 1K, behind a single HTTP endpoint. Billed per image in credits, refunded automatically when a job fails.

  from 2 credits ≈ $0.025 per image

• Nano Banana Pro API

  nanobanana-pro

  Higher-fidelity generation for hero shots and print-sized crops, with 1K, 2K and 4K output — roughly twice the base price per image at 1K.

  from 4 credits ≈ $0.05 per image

• Qwen-Image 2.0 API

  qwen-image-2

  Qwen-Image 2.0 from Alibaba — an image model built around legible in-image text, including Chinese, with reference-image input and 1K or 2K output.

  from 3 credits ≈ $0.038 per image

• Qwen-Image Max API

  qwen-image-max

  Qwen-Image Max — the flagship of Alibaba's Qwen-Image line, with reference-image input, 1K and 2K output and a fixed set of five aspect ratios.

  from 8 credits ≈ $0.10 per image

• Wan 2.7 Image API

  wan-2-7-image

  wan2.7-image from Alibaba's Tongyi Wanxiang line — text-to-image and reference-image generation at 1K or 2K, on the same endpoint and API key as every other model here.

  from 2 credits ≈ $0.025 per image