ByteDance Seed

OpenRouter files this team's models under two author ids, bytedance-seed and bytedance, and the second one holds exactly one row: bytedance/ui-tars-1.5-7b. The split is a router artefact, not two organisations. OpenRouter's own page for that row links its weights to huggingface.co/ByteDance-Seed/UI-TARS-1.5-7B — the same Hugging Face organisation the Seed models are published from. ByteDance's namespaces are inconsistent about it in both directions: the UI-TARS weights sit under ByteDance-Seed, while the code for the same model sits under github.com/bytedance/UI-TARS. A router that keys on the publishing prefix inherits that inconsistency and turns it into two vendors.

The UI-TARS row is also the weakest artefact of the line that produced it, which is invisible from the catalog. Its model card compares three checkpoints on OSWorld and puts the released UI-TARS-1.5-7B at 27.5 against 42.5 for the UI-TARS-1.5 the blog headlines — the larger model was offered only as "early research access" by writing to TARS@bytedance.com. Then on 2025-09-04 the team announced UI-TARS-2, "a major upgrade from UI-TARS-1.5" spanning GUI, games, code and tool use. That was a year ago, and the router still shows the April 2025 7B. Its window is 128000tokensopenrouter-models, last checked 2026-09-14 against 262144tokensopenrouter-models, last checked 2026-09-14 on the newest Seed row, and reading the two prefixes as separate vendors hides that these are the same team's oldest and newest listings.

What the bytedance-seed prefix carries is a narrow slice of what Seed ships. The team's own model menu names six things: Seed2.1, Seedance 2.5, Seedream 5.0 Pro, SeedRealtime, Seed Audio 1.0 and Seed GR-RL. Its blog index served nine posts on 2026-09-06, dated 9 April to 5 August 2026; two announce a text model — Seed2.1 and its preview four days earlier — and the other seven are speech, audio, image, video and 3D work, or frontier research. A language-model router can list one of those categories, so the six rows in the catalog as observed on 5 September 2026 were not a partial view of ByteDance Seed. They were the only view a price-and-context table is capable of.

Within that slice the router carries the junior half. Seed2.1 arrived on 2026-06-23 as "two AI productivity models in different sizes: Pro and Turbo", and Turbo is the one with a row. That is not the router being selective: the vendor's own Seed2.1 page has four buttons, and both "Try it" and "API" point at BytePlus's dola-seed-2-1-turbo. Pro has no link to click anywhere on the page. Yet the comparison table further down that same page is Pro's: of its twenty-three benchmarks Turbo comes out ahead on two — BeyondAIME, 88.0 to 87.0, and Workspace Bench, 54.7 to 53.0 — and trails on the other twenty-one. The model you can actually call abroad is the one the vendor benchmarks second.

The naming is worth writing down once, because the same family answers to four strings depending on where you meet it. The research site calls it Seed2.1. The release post says "Doubao and Volcano Engine users can now start to access Doubao Seed 2.1". BytePlus sells it as dola-seed-2-1-turbo. OpenRouter calls it bytedance-seed/seed-2-1-turbo. That is not branding trivia: neither doubao nor dola occurs anywhere in the OpenRouter snapshot of 5 September 2026, so the two names ByteDance actually ships this model under at home and abroad are both unsearchable in the one table a router user has.