Seedream 5.0 Flash – Flux1 AI API

The fast, low-cost Seedream 5.0 tier. Generate or edit images up to 2K in seconds at one flat price.

ByteDanceimage

Model id: seedream-5-0-flash
Price: 3 credits / image
Output: 1K–2K
Reference images: Up to 10
Typical time: 10–20 seconds

Aspect ratios

auto1:14:33:416:99:163:22:32:11:221:9

POST/api/v1/generations

JSON requestAsynchronousOne image per request

3 credits per image at every quality setting. Reference images do not add an extra charge. Check credits_refunded to confirm a refund; unresolved submissions may require review.

Jump to request examples ↓

Authorization

Authorizationstringrequired

Bearer fx1_live_… — send your API key in the request header. Requires a completed paid purchase; new generations also require enough credits.

Idempotency-Keystringoptional

Use one unique value per generation and reuse it with the same body on retries. Printable ASCII, no spaces. A different body with the same key returns 409.

Maximum length: 128 characters

Manage API keys ↗

Request body

modelstringrequired

Use this exact model ID in the top-level request body.

seedream-5-0-flash

promptstringrequired

Describe the image to create, or the changes to make to your reference images. Whitespace is trimmed.

Maximum length: 5,000 characters

imagesstring[]optional

Optional reference images. Use publicly accessible HTTPS URLs or data:image/* base64 URIs (up to 20,000,000 characters per entry). Omit for text-to-image.

Maximum items: 10

aspect_ratiostringoptional

Output width-to-height ratio. Auto lets the model choose.

Default: 1:1

auto1:14:33:416:99:163:22:32:11:221:9

resolutionstringoptional

Output resolution tier; values are case-insensitive. Omit or leave empty to use the default.

Default: 2K

1K1.5K2K

Response & next step

A successful submission returns 202 and a generation id. Poll GET /api/v1/generations/{id} every 2–3 seconds until the status is succeeded or failed.

Read the result URL from output.images[0].url. Download it before expires_at (30 days after storage). On failure, inspect error and credits_refunded.

Generation lifecycle →Error reference →

Build your request

3 credits / image

ModeResolution

Examples only. Run on your server with your API key.

# Set FLUX1_IDEMPOTENCY_KEY once per generation; reuse it on retries.
curl --request POST 'https://flux1.ai/api/v1/generations' \
  --header "Authorization: Bearer $FLUX1_API_KEY" \
  --header 'Content-Type: application/json' \
  --header "Idempotency-Key: ${FLUX1_IDEMPOTENCY_KEY:?Set a unique key for this generation}" \
  --data '{
  "model": "seedream-5-0-flash",
  "prompt": "A ceramic cup on a linen table, soft morning light",
  "aspect_ratio": "1:1",
  "resolution": "2K"
}'

202 · POST /api/v1/generations

{
  "id": "gen_example",
  "status": "queued",
  "model": "seedream-5-0-flash",
  "media_type": "image",
  "credits": 3,
  "credits_refunded": false,
  "input": {
    "prompt": "A ceramic cup on a linen table, soft morning light",
    "aspect_ratio": "1:1",
    "resolution": "2K"
  },
  "output": null,
  "expires_at": null,
  "content_expired": false,
  "error": null,
  "created_at": "2026-09-07T08:00:00.000Z",
  "completed_at": null
}

Model notes

seedream-5-0-flash is Seedream 5.0 Flash, the fast tier of the Seedream 5.0 family. For the final pass on a dense layout, send the same body to seedream-5-0-pro.
Every resolution tier (1K, 1.5K, 2K) costs the same, so the default is 2K. Reference images do not change the price.
It accepts the same aspect ratios as Seedream 5.0 Pro, and references as HTTPS URLs or data:image/…;base64, URIs. Omit images for text-to-image.
Fields this model does not use are ignored.