On the afternoon of November 9, 2026, ByteDance's Seed team released the image model Seedream 5.5: the official blog is titled "More Realistic Images, More Stable Editing Across 100 Rounds," with the X announcement going out the same day. Exactly 124 days after the previous flagship, 5.0 Pro. It's the fourth Seedream release in a year — 4.5 (December 2025), 5.0 Lite (February 2026), 5.0 Pro (July 2026), and now 5.5.
Unlike 5.0 Pro, which came to Volcano Ark first and apps later, all four channels opened the same day this time: Dreamina, Doubao, Doubao Work and the Volcano Ark experience center. The first Chinese media reports appeared from 18:20 Beijing time (Cocoloop 18:20, Jiemian News 18:22, Guandian 19:08). Third parties followed the same evening: WaveSpeed listed three 5.5 endpoints that night (text-to-image, editing, layer decomposition), and Quantslant ran a 35-image test on WaveSpeed the same night. The next day Doubao announced its image-design upgrade with 5.5; BytePlus launched its product page and image packs; ComfyUI v0.45.0 shipped with a Seedream 5.5 Partner Node.
But launch day had a gap: no official API model ID or price. BytePlus's ModelArk price list that day still stopped at the 5.0 models, and the Volcano Ark API was promised "this week." The gap was filled on the China side on Nov 12 (price list public); the international side is still waiting as of Nov 14. See our API access status article for details.
The official blog makes three claims. First, steadier multi-round editing: targeted training keeps non-edited areas pixel-identical and eliminates color drift, reducing detail loss and quality degradation across rounds, supporting up to 100 rounds of continuous work on one piece. Second, native RGBA: direct output of images with an alpha channel, fully and semi-transparent, with edges and transparent areas handled by the model — assets go straight into downstream design workflows without cutouts or edge cleanup; transparent assets can be generated from text or reference images. Third, more realistic images and clearer text: more natural lighting, materials and skin textures, less excessive gloss, overexposure and mottled texture; more accurate dense small text and complex glyphs (Chinese and English).
The blog also gives vendor evaluation numbers: usability rates across six production scenarios (e-commerce, marketing, film, gaming, office, fashion design) all improved over 5.0 Pro, with film and office more than doubling; image-to-image realism GSB score +55.62% vs 5.0 Pro; text breakage severe 0.4%, minor 1.7%. But these are all ByteDance's own numbers: reviewer count, prompt set, sample size, blinding protocol and confidence intervals are all unpublished. The blog doesn't say who runs MagicArena either.
Seedream iterates fast: 4.5 on December 3, 2025, 5.0 Lite on February 24, 2026 (83 days after 4.5), 5.0 Pro on July 8 (134 days after 5.0 Lite), 5.5 on November 9 (exactly 124 days after 5.0 Pro). 5.0 Pro's launch day also brought the layer-decomposition endpoint (up to 16 layers); 5.5 expands it to about 100 layers. Note the 5.0 family splits roles: Pro is the flagship, but Lite actually has 2K/3K/4K tiers and up to 14 reference images (at the cost of the worst small text), and Flash is the fast tier. 5.5 didn't carry over Lite's 4K tier — it tops out at 2K.
Seedream is ByteDance Seed's image line, paired with the Seedance video line (latest: Seedance 2.5 from July 31). At launch, Seedream was already embedded across ByteDance's consumer surfaces: Dreamina (creation), Doubao (chat), Doubao Work (office), CapCut (video editing), Volcano Ark (China cloud API) and BytePlus (international cloud API). The official blog also teased Seedream 5.5 Pro — only "A Pro version of the Seedream 5.5 series will follow," with no date or specs.
On launch day, neither AA board nor Design Arena listed 5.5; independent scores arrived Nov 11: AA text-to-image 1135 (#10), editing 1159 (#6). The first tests agree: editing is much steadier than the previous generation, cutouts are clean, but glass, water and other see-through objects come out essentially opaque in practice; text looks good in small samples — and the samples are all small. Quantslant's same-night 35-image test is the most representative: transparency 10/10 genuine RGBA, glass and water 0/4 see-through. What to watch next: BytePlus's official international price and model ID, an independent 100-round reproduction, news of 5.5 Pro, and how the AA scores move with votes. This site will keep tracking it.
Reference: ByteDance Seed — More Realistic Images, More Stable Editing Across 100 Rounds | Introducing Seedream 5.5 (rewritten and organized by ModelBrief; facts per the official source)