Seedream 4.0 API

Introduction

Seedream 4.0 Text-to-Image turns a written art-direction brief into a new image. Use it when composition, subject hierarchy and visual style are still open creative decisions rather than properties inherited from a source image.

Choose a Seedream 4.0 mode by starting material

Key features

Image creation and source-led revision

Seedream 4.0 supports both starting from a written visual brief and revising supplied imagery. Keep those jobs separate: creation establishes a new composition, while editing is judged against the source elements it should retain.

Design work needs a reviewable hierarchy

For a graphic or campaign concept, provide checked copy and define the visual hierarchy before styling details. Review legibility, placement and factual accuracy at the intended delivery format.

A visual result is not a factual source

Use generated imagery to discuss a design direction. Do not treat an attractive result as proof of product details, dimensions or real-world claims that were not independently verified.

Request parameters

Pricing

Prices are in credits, the same credits you use on the website (1 credit = $0.01). The hold is taken when the task is accepted and settled to the actual charge when it finishes; failed tasks are refunded.

Each task is rounded up to whole credits, so one run at the lowest tier costs 5 credits per image ($0.05).

For an exact number before you run, send the same body to POST /jobs/quote.

Use cases

Start from a written brief

Seedream 4.0 Text to Image renders a brief into a single image at a size you name. Pick one of the sixteen presets, from 1024*1024 up to 4096*2304, before you write, then describe the subject, composition and light for that shape.

Consistent characters from references

Send a face reference, a wardrobe reference and a background plate to the editing endpoint, name what each contributes, and get one frame back at the preset you chose.

Continuing work started on 4.0

Campaigns and character sets first made with Seedream 4.0 can stay on the same model instead of switching generations halfway and re-matching the style.

Prompt guide & pro tips

Write the brief, or name the references

For text-to-image, describe subject, wardrobe, setting and light in one prompt. For editing, send one to ten image URLs and say what each one contributes and what must stay.

Poll the task and keep the brief

There is no seed, so store the prompt with any frame you want to extend into a series.

Adapt the included example

Start with the published example using size: 2048*2048. Replace the subject and creative direction while keeping the input contract for this mode intact.

Check the result before iterating

size is the whole framing control: there is no aspect ratio field, no seed and no file-format switch. The sixteen presets are the complete list, and anything outside them is rejected before the request leaves the platform. A portrait brief forced into a wide preset comes back with dead space.

API quick start

Call the Seedream 4.0 API in three steps

1. Create an API key. Sign in to PopNow and create a key in the API console. Keys start with sk-popnow- and use the same credits as the website.
2. Send the request. POST /jobs/createTask with model bytedance/seedream-4.0/text-to-image and an input object that follows the parameter table. The response returns a task ID straight away.
3. Get the result. Poll GET /jobs/recordInfo with the task ID, or pass a callBackUrl and we post the result to it. Download the output links when the task succeeds.

# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(uuidgen)"
curl -X POST https://api.popnow.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $IDEMPOTENCY_KEY" \
  -d '{
  "model": "bytedance/seedream-4.0/text-to-image",
  "input": {
    "prompt": "A ceramic teapot on a linen cloth, soft window light, muted palette",
    "size": "2048*2048"
  }
}'

# 2. Copy data.taskId from the response, then poll until state is succeeded, failed, canceled or expired.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

Replace the prompt and any links with your own. The API tab has the response, polling and callback reference.

Seedream 4.0 API questions

All Seedream models

Seedream 5.0 Pro and Lite are the newer generation with finer material detail; 4.0 keeps its own look and the largest sizes.

• Seedream 5.0 Pro APIHigh-detail images and edits from up to ten referencesFrom 6 credits per image
• Seedream 5.0 Flash APIQuick Seedream images, edits and layer splits up to 2KFrom 4 credits per image
• Seedream 5.0 Lite APIFixed-size 2K frames that keep a series consistentFrom 6 credits per image
• Seedream 4.0 APIExact sizes up to 4096×2304 and ten-reference editsFrom 5 credits per image

Other image APIs

• Nano Banana 2.1 APIGoogle's newest Nano Banana, sharp text and 4K outputFrom 8 credits per image
• Nano Banana Pro APIPlans the layout first: dense text, diagrams and 4K editsFrom 17 credits per image
• GPT Image 2.5 Sunburst APIOpenAI's quality-first model, up to 4K with clean textFrom 1 credit per image
• FLUX.2 Max APITop-tier FLUX: photoreal light and exact brand colorsFrom 11 credits per image
• Qwen Image 2.1 Pro APIUp to six detailed 2K images from one promptFrom 6 credits per image
• Qwen Image 2.1 Turbo APIFast 8-step renders, up to six per promptFrom 3 credits per image

More about Seedream 4.0

Try it

Seedream 4.0 AI Image Generator onlineCreate images with Seedream 4.0 in PopNow

Docs

Seedream 4.0 model ID and input schema in the API docsPopNow API quickstart: your first request in five minutesImage generation guide for the PopNow APIWebhooks: get Seedream 4.0 results without polling