Seed 2.1 Pro
Released Jun 23, 2026 · knowledge cutoff unpublished
- Status
- Unknown
- Location
- China
- Modality
- Multimodal
- Context window
- 256K
- Max output
- —
- Speed
- —
- Price ($/MTok in / out)
- $0.83 / $4.14
- Cost per task
- —
- Open weights
- No
Benchmarks0 of 8 reported
MMLU-Pro
GPQA Diamond
SWE-bench Verified
Terminal-Bench 2.1
AIME (latest)
Humanity's Last Exam
LMArena Elo
ARC-AGI-2
Strengths & weaknesses
Strengths
- ByteDance's launch framing shifts from Seed 2.0's broad multimodal upgrade to a narrower, workflow-oriented bar: whether the model can carry one real task from requirement to validated result
- A preview build placed level with Claude Opus 4.6 on the Code Arena frontend leaderboard within days of release
- Ships as a paired Pro/Turbo lineup from day one, so a lower-cost, lower-latency sibling is available immediately rather than following months later
Weaknesses
- No model card or benchmark table has been published at launch — every capability claim so far is qualitative ('leading', 'comparable to GPT-5.5') rather than a disclosed number
- Parameter counts and knowledge cutoff remain undisclosed, unlike the detailed technical report ByteDance published for Seed 2.0
- Too new for independent benchmark or arena coverage beyond a single preview-build leaderboard placement
Officially launched 2026-06-23 at Volcano Engine's FORCE conference (seed.bytedance.com/en/blog/seed2-1-officially-released-advancing-ai-productivity); ByteDance's own post makes only qualitative claims (leads Terminal-Bench 2.1, SWE-Bench Pro, SciCode, OSWorld, MobileWorld, MMMU-Pro among named benchmarks) without publishing a benchmark table or model card, unlike Seed 2.0 — so all eight tracked benchmark fields are left null rather than guessed from prose. A Seed 2.1 Pro preview build ranked 8th on arena.ai's Code Arena frontend leaderboard with a score of 1539, level with Claude Opus 4.6, but that is a different (frontend-coding) leaderboard from the tracked overall text lmarenaElo, so left null here too. Context window (256K) is corroborated across multiple third-party API trackers citing Volcano Engine's model list; max output could not be pinned to a reliable single figure and is left null. Pricing (¥6/¥30 per MTok ≈ $0.83/$4.14) is from ByteDance's own announcement; Seed 2.1 Turbo is priced at half the Pro rate.
For developers
API model strings
- volcengine
doubao-seed-2.1-pro
Licence
Proprietary — weights not released
Retirement
No retirement announced
Lineage
No recorded predecessor