Seedream 5.5 Release: What ByteDance Confirmed — and What to Do Today

Seedream 5.5 promises edits that hold still for 100 rounds, plus transparent assets. The model string you can send today is still 5.0.

Seedream 5.5 is ByteDance Seed’s new image-creation model, announced on 9 November 2026. It is for teams who already ship product shots, posters, and edits on Seedream 5.0 and need to know whether to switch. Do not switch a production route yet. The launch names three upgrades and a vendor evaluation. It does not name an API ID, a price, a resolution cap, or a license.

If a job has to ship this week, open Seedream 5.0 Pro and run that card. Seedream 5.5 is not behind the link.

Key takeaway

• On 9 November 2026 ByteDance Seed introduced Seedream 5.5 with three claims: pixel-level preservation of unedited regions in a 100-edit demo, native RGBA including partial transparency, and more natural light, materials, and skin plus clearer dense small text.
• MagicArena scores in that post are vendor-run. They include a +55.62% GSB on image-to-image realism versus Seedream 5.0 Pro, and text-corruption rates of 0.4% severe and 1.7% minor.
• No 5.5 model ID appeared on the Seed post, on Volcano Ark’s November release table, or on Ark’s image price table. SandBase returned “Model Not Found” for the 5.5 paths checked that day.
• SandBase lists Seedream 5.0 Pro at $0.09 per image and Seedream 5.0 Flash at $0.018 per image. A Pro tier of the 5.5 series is promised and not dated.

Where Seedream is today

The generation with a model card is still 5.0. These pages describe that family. Companion notes in this series are at the end.

• Seedream 5.0 Pro introduction and the Fast versus Pro cost note: what you can call, and how the two tiers were framed.
• Seedream versus Qwen Image versus Nano Banana: an earlier three-way look. Not a 5.5 result.
• Cards: Seedream 5.0 Pro for finals, Seedream 5.0 Flash for drafts, and Seedream 5.0 Pro Fast, which returned HTTP 200. This note does not quote a Pro Fast price. ByteDance’s SandBase catalog home is the vendor page. There is no 5.5 card to link.
• The call shape is the run API. No key yet: getting started.

The number that matters is not 100. It is whether a request can name the model.

What is confirmed

ByteDance Seed launch post for Seedream 5.5 (retrieved 9 Nov 2026). Source: seed.bytedance.com.

Confirmed means a primary page said it, and we retrieved that page on 9 November 2026.

SandBase returned Model Not Found for /models/bytedance/seedream/5.5/pro (captured 9 Nov 2026). Cookie dialog cropped from the bottom edge.

Seedream 5.0 Pro’s SandBase card, same day, shows ID bytedance/seedream/5.0/pro, $0.09 per image, one image per request, jpeg or png, and aspect ratios for what the card calls a 2K image: 21:9, 16:9, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 9:16. Default aspect is 1:1. Failed runs are not charged. The playground showed a saved example and a displayed estimate of $0.09. That portrait is the page’s sample, not a generation from this article.

SandBase Seedream 5.0 Pro card on 9 Nov 2026: ID bytedance/seedream/5.0/pro, displayed run estimate $0.09. This is the callable route, not 5.5.

The Flash card lists $0.018 per image and describes roughly a 15 to 20 second turnaround. That timing is the card’s own wording, not a stopwatch from this desk. Listed Flash price is one fifth of listed Pro price. That is a price ratio, not a quality score.

Ark’s 5.0 tutorial, updated 2 November 2026, documents doubao-seedream-5-0-pro-260628 and doubao-seedream-5-0-flash-260915: text-to-image, reference images, coordinate edits, a layer split into one base plus up to 16 layers, png or jpeg, 1K / 1.5K / 2K, 500 images per minute. Those are 5.0 facts. They are not 5.5 specs. Ark’s price page puts 5.0 Pro output at 0.30 yuan per image at or under 2.61 megapixels and 0.60 yuan above that. First input image free, later inputs 0.02 yuan. Flash output is 0.12 yuan. SandBase’s dollar prices are a different bill. Do not add them together.

What the three upgrades claim

Edits that are supposed to hold unedited pixels. Seed says 5.5 was trained to keep unedited regions at the pixel level, drop color shift there, and slow the decay that stacks when each output becomes the next input. The demo is 100 rounds on one person: clothes, accessories, and tabletop objects change; rings and eyeglass frames still take edits; pose, skin contact, occlusion, and light are accounted for. Other sequences cover flowers (including lace and beads) and a room whose furniture moves while perspective and shadows stay coherent. The product page adds hair, a watch face, and a painting. “Pixel level” is their description of the demo. The post does not publish a mask, a diff, or the instruction list.

Native RGBA, including partial transparency. Seed says the model emits an alpha channel, full or partial, with edges and interior gaps handled well enough to skip a separate cutout. Demos include a snowy owl’s separated feathers, lettering drawn from a reference material onto a transparent field, sticker sets, and characters reused across scenes. File container, premultiplication, and the request field are not named.

Light, skin, and dense small text. Seed says gloss, overexposure, and blotchy texture are reduced. The post describes portraits with held shadow detail, a curtain on a rough wall, and a wet racetrack. For text it shows a newspaper-style Shakespeare page in English and a butterfly infographic with small Chinese captions. Those are published examples, not a pass rate.

What we do not know

A wrong number is worse than a blank cell. None of the following was on the Seed post or the Ark pages checked on 9 November 2026:

• API model ID, on Ark or on SandBase
• Price per image, and whether text tokens are free
• Maximum resolution, aspect ratios, reference-image cap, rate limit
• License and whether weights are open
• The request field that turns on RGBA, and the file format of the alpha
• How “pixel level” was measured
• MagicArena prompt count, judge count, and the formula behind +55.62%
• The usability rates underneath “more than twice” for film and office
• The other models’ text-corruption rates
• When the promised 5.5 Pro tier ships, and whether Flash-style 5.5 exists
• Whether Jimeng, Doubao, Doubao Work, or the Ark console actually show 5.5

IT Home wrote on 9 November that 5.5 was rolling out on Jimeng, Doubao, Doubao Work, and Volcano Ark, and that a 2K square edit cost about 0.28 yuan, under half of 5.0 Pro. PANews reported a Jimeng, Doubao, and Ark rollout and did not print an official price table. We did not see those product UIs. Ark’s published 5.0 Pro output rate at or under 2.61 megapixels is 0.30 yuan, so “about 0.28, under half of Pro” does not match that rate in any obvious way. Leave both figures out of a budget.

How to read the MagicArena chart

Seed scored six uses: e-commerce, marketing, film and television, gaming, office, and fashion. Evaluators on MagicArena scored quality and usability. Versus 5.0 Pro, both rose in all six, and film and office usability were more than twice the previous version. Without the base rate, “twice” can still be a low number.

Pairwise scores use Good / Same / Bad. All four comparisons versus the previous version were positive: text structure and realism, each for text-to-image and image-to-image. The only percentage in the prose is +55.62% for image-to-image realism versus 5.0 Pro. Against GPT Image 2.5 Sunburst and Nano Banana 2.1, Seed says 5.5 leads on text structure in both task types and has a substantial text-to-image realism advantage. Severe text corruption is 0.4%. Minor is 1.7%. Both cover Chinese and English, including dense small text, and both are described as much lower than the previous version.

That block is ByteDance judging ByteDance’s demo set. It is not a public leaderboard we re-ran, and it is not GPT Image 2.6, which shipped later and is not the model named in the chart. The comparison keeps those names apart from the October poster test we actually ran on earlier models.

Try today on SandBase

Generated with Seedream 5.0 Pro on SandBase (bytedance/seedream/5.0/pro), not 5.5. Exact strings: STAY COLD 24 HOURS / $39.99.

API status, 9 November 2026: Seedream 5.5 has no published model ID and no price. This is not a 5.5 API guide. Call 5.0 Pro or Flash.

The Pro card’s documented call is POST /v1/run, then GET /v1/run/{id} until status is completed, failed, or timeout. Inputs on that card are prompt (required), aspect_ratio, num_images (minimum 1, maximum 1), and output_format (jpeg or png). This sample follows that schema. It is not a captured 5.5 response, and this article does not claim a fresh generation.

import os
import time
import requests

API_KEY = os.environ["SANDBASE_API_KEY"]
HEADERS = {
    "Authorization": f"Bearer {API_KEY}",
    "Content-Type": "application/json",
}

def run_image(model: str, prompt: str) -> str:
    submit = requests.post(
        "https://api.sandbase.ai/v1/run",
        headers=HEADERS,
        json={
            "model": model,
            "prompt": prompt,
            "aspect_ratio": "1:1",
            "num_images": 1,
            "output_format": "png",
        },
        timeout=60,
    )
    submit.raise_for_status()
    payload = submit.json()
    run_id = payload["id"]
    status = payload.get("status")
    for _ in range(120):
        if status in ("completed", "failed", "timeout"):
            break
        time.sleep(2)
        polled = requests.get(
            f"https://api.sandbase.ai/v1/run/{run_id}",
            headers={"Authorization": f"Bearer {API_KEY}"},
            timeout=60,
        )
        polled.raise_for_status()
        payload = polled.json()
        status = payload.get("status")
    if status != "completed":
        raise RuntimeError(f"Generation ended: {status}")
    return payload["outputs"][0]["url"]

prompt = (
    "Square studio product photo of a matte black bottle on a light gray background. "
    'Headline exactly: "STAY COLD 24 HOURS". Price exactly: "$39.99". No other text.'
)
print(run_image("bytedance/seedream/5.0/pro", prompt))

Drafts use the same function with "bytedance/seedream/5.0/flash". At the listed card prices, 100 Pro frames are $9.00 and 100 Flash frames are $1.80. There is no seedream-5.5 string to drop in. When a card appears, rerun this prompt and keep both files. The sticker and poster workflow is the checklist for text and alpha. The October exact-text study is the baseline method, not a 5.5 score.

I would keep logos, prices, and faces on 5.0 Pro until a primary page prints an ID, a price, and what “pixel level” and “RGBA” mean as parameters.

FAQ

Is Seedream 5.5 on an API?

Not in any primary source checked on 9 November 2026. The Seed post and product page announce it and do not list an ID. Ark’s November release table and image price table do not list it. SandBase returns “Model Not Found” for the 5.5 paths we requested. Press reports of a consumer rollout are unverified here.

What is new versus Seedream 5.0 Pro?

Seed names three upgrades: more stable multi-turn edits with unedited regions held at the pixel level, native RGBA with partial transparency, and more realistic light, materials, and skin plus clearer dense small text. A 5.5 Pro tier is planned. Resolution, languages, rate limits, and price for 5.5 were not published, so they are not “the same as 5.0”.

Does it output a transparent PNG?

Seed says it generates an alpha channel directly, including partial transparency, so a cutout step can be skipped. The post does not name the container or the parameter. Treat transparent PNG as the intended workflow, not as a confirmed response field.

Can I trust the Sunburst and Nano Banana 2.1 comparison?

You can trust that ByteDance published a preference for 5.5 on text structure, and a substantial text-to-image realism advantage, against those two names. You cannot see the prompt list. It is not an independent test, and it is not GPT Image 2.6.

What do I call today?

Seedream 5.0 Pro at $0.09 when the frame ships. Seedream 5.0 Flash at $0.018 when you are still choosing a crop. Both cards were HTTP 200 on SandBase on 9 November 2026.

Stay in the Seedream cluster: the 5.0 Pro introduction, the Fast versus Pro note, and Seedream versus Qwen Image versus Nano Banana.

Related reading

• Seedream 5.5 versus Sunburst and Nano Banana 2.1: the vendor chart, kept separate from routes you can call.
• E-commerce text and transparent stickers: posters and RGBA before a 5.5 ID exists.

Still unverified, and the next click

This note contains no Seedream 5.5 image. We did not diff the 100-round demo. Chart digits that appear only in graphics, beyond the figures quoted above, stay unread.

Sign in, or start from the model catalog, and send the prompt you would have sent to 5.5 through Seedream 5.0 Pro. Archive the file. That pair is the comparison that will matter once 5.5 can be named in a request.