Doubao Seed 2.1 Pro vs Kimi K3
Doubao Seed 2.1 Pro wins on Overall, Coding, Multimodal. Every numeric field is compared below, with a worked monthly-cost example and a pick rule for each use case.
Verdict at a glance
Choose Doubao Seed 2.1 Pro if you…
- World-leading video understanding
- Excellent Chinese
- Strong agent ability
- Full 256K context
- Best for: Video understanding, Chinese tasks, AI agents
Choose Kimi K3 if you…
- Best-in-class long text
- Open-source and self-hostable
- Strong codebase understanding
- Fair price
- Best for: Long-document reading, Codebase analysis, Chinese
Head-to-head aggregate scores
Scores are 0–100, aggregated from public benchmark information and independently weighted across three leaderboards. Rank is out of 22 tracked models.
Aggregated from public sources and independently weighted; methodology on the Terms page. Scores within 3 points are treated as statistically tied.
Specs & pricing — every field side by side
List API prices in USD per 1M tokens. The highlighted cell is the stronger value/capability on that row.
| Dimension | Doubao Seed 2.1 Pro | Kimi K3 | Verdict |
|---|---|---|---|
| Vendor | ByteDance (CN) | Moonshot AI (CN) | Different vendors |
| Released | 2026.06 | 2026.06 | Kimi K3 is newer |
| Overall (rank) | 78 · #7 | 77 · #8 | Doubao Seed 2.1 Pro +1 |
| Coding | 76 · #7 | 71 · #11 | Doubao Seed 2.1 Pro +5 |
| Multimodal | 92 · #2 | 81 · #10 | Doubao Seed 2.1 Pro +11 |
| Context window | 256K | 256K | Tie |
| Max output | 256K | 64K | Kimi K3 longer |
| Effective-context | 93 | 99 | Kimi K3 more reliable |
| Input $/1M | $0.83 | $3 | Doubao Seed 2.1 Pro cheaper |
| Output $/1M | $4.17 | $15 | Doubao Seed 2.1 Pro cheaper |
| Cache discount | custom | custom | Tie |
| Speed | ~65 tok/s | ~45 tok/s | Doubao Seed 2.1 Pro faster |
| TTFT | 0.5s | 0.7s | Doubao Seed 2.1 Pro snappier |
| Function calling | 85 | 80 | Doubao Seed 2.1 Pro ahead |
| Refusal rate | ~11% | ~6% | Kimi K3 less restrictive |
| English | 72 | 75 | Kimi K3 |
| Chinese | 95 | 92 | Doubao Seed 2.1 Pro |
| Modalities | text, image, video | text, image | different coverage |
| Open weights | No | Yes | Kimi K3 is open |
| Fine-tuning | Yes | No | |
| Free tier | Doubao App free; free quota on the Ark platform | Kimi App free; free quota on the open platform | |
| SOC2 / no-train | no / yes | no / yes | |
| Private deployment | Yes | Yes | Both support it |
Fields drawn from vendor public documentation and the Modelspectra 22-model dataset; speed varies with network, concurrency and prompt length. Verify current pricing before purchase.
Dimension-by-dimension analysis
Reasoning & overall intelligence
Doubao Seed 2.1 Pro leads the overall aggregate by 1 points (78 vs 77). That is a meaningful, not marginal, edge on hard, multi-step reasoning, while Kimi K3 remains a strong generalist that is not out of its depth on routine work.
Agentic coding
This is a modest gap: Doubao Seed 2.1 Pro scores 76 against 71. On multi-file edits, SWE-style tickets and long-horizon agent loops Doubao Seed 2.1 Pro needs fewer correction turns; Kimi K3 is still competent for scripts and assisted completion but trails as task complexity rises.
Multimodal
Doubao Seed 2.1 Pro leads multimodal 92 vs 81. A concrete modality difference: Doubao Seed 2.1 Pro additionally handles video.
Speed & latency
Doubao Seed 2.1 Pro is faster in interactive use: ~65 tok/s with 0.5s TTFT versus ~45 tok/s with 0.7s TTFT (about 1.4× the throughput). For conversational UIs where perceived responsiveness drives retention, that edge is a real product factor even when raw reasoning is lower.
Context: window vs usable recall
Nominal windows are 256K for Doubao Seed 2.1 Pro and 256K for Kimi K3. Crucially, the larger nominal window does not win on usable recall: Doubao Seed 2.1 Pro advertises 256K but Kimi K3 scores higher on effective-context (99 vs 93), i.e. it actually retains more of what it was given.
Price & total cost
Doubao Seed 2.1 Pro is the cheaper API at $0.83/$4.17 versus Kimi K3 at $3/$15 per 1M input/output tokens — list input is about 3.6× lower.
Chinese vs English
English: Doubao Seed 2.1 Pro 72 vs Kimi K3 75. Chinese: 95 vs 92. For Chinese-language production, Doubao Seed 2.1 Pro is the stronger pick. Note that non-Chinese models generally require overseas network access for their APIs.
Tool use & ecosystem
Function-calling score: Doubao Seed 2.1 Pro 85 vs Kimi K3 80, so Doubao Seed 2.1 Pro has the edge on structured tool use. Fine-tuning is available from Doubao Seed 2.1 Pro. Factor in existing SDK/plugin familiarity — switching cost often outweighs a few-point tool-use gap.
Cost worked example — same workload, real token math
Assume a production workload of 100M input + 30M output tokens per month, with 90% of input tokens served from cache. Figures use public list prices.
| Scenario · per month | Doubao Seed 2.1 Pro | Kimi K3 | Gap |
|---|---|---|---|
| List priceno cache applied | $208100M in × $0.83 + 30M out × $4.17 | $750100M in × $3 + 30M out × $15 | 3.61×gap |
| With caching90% of inputs cache-hit | $208no published cache discount | $750no published cache discount | 3.61×gap |
Illustrative model; your input/output mix and cache-hit ratio change the result. Prices are list rates before any enterprise agreement.