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TL;DR

Moonshot AI launched Kimi K3.1 Pro on October 23, and Artificial Analysis ranked it fourth on its Intelligence Index, three points behind the top score. Its price is lower than the leading model’s, but its weights are only promised for November 4, its licence has not been published, and several prominent capability claims come from Moonshot’s own tests.

Moonshot AI launched Kimi K3.1 Pro on October 23, and an evaluation by Artificial Analysis placed it fourth on its Intelligence Index, three points behind the leading model. The result puts the model near the top of current proprietary systems on that benchmark, while its promised open weights and unpublished licence mean it is not yet available for independent deployment.

Artificial Analysis gave K3.1 Pro an Intelligence Index score of 55.1, compared with 57.6 for Claude Opus 5.5, 56.0 for Claude Sonnet 5.5 and 55.8 for Muse Wonder Full. The evaluator’s figures, reported as of October 24 with models at their highest reasoning settings, put K3.1 Pro ahead of GPT-6 Astra at 52.7. It lists the model as “promised by Nov 4”, rather than available open weights.

The evaluator lists K3.1 Pro as a mixture-of-experts model with 2.8 trillion total parameters and 104 billion active parameters, a one-million-token context window, and text and image input. Moonshot made it available through the Kimi apps, Kimi Work, Kimi Code and its API. Artificial Analysis lists API prices of $2 per million input tokens and $10 per million output tokens. It estimates about $2.11 per Intelligence Index task, compared with $5.98 for Claude Opus 5.5 under the evaluated settings; task costs depend on the evaluator’s benchmark method and are not a general price for every use.

The sharpest measured gain over Kimi K3 is on agentic coding: Artificial Analysis recorded 67% on Terminal-Bench 4.0, against 13% for K3, the highest score in its listed comparison. K3.1 Pro scored 1,846 Elo on GDPval-AA, behind Opus 5.5 and Muse Wonder Full. On Humanity’s Last Exam it scored 52%, below Opus 5.5 at 61%. Artificial Analysis also measured a lower hallucination rate on its AA-Omniscience evaluation: 44%, down from 53% for K3.

At a glance
reportWhen: Launched October 23, 2026; benchmark de…
The developmentKimi K3.1 Pro entered Moonshot’s apps and API, with independent benchmark results placing it close to leading proprietary models.
Thorsten Meyer AI
Moonshot AI · 23 Oct 2026

Infographic 01 · Claimed vs. measured

Moonshot says “matches the strongest.” Independent tests say: close.

The KPIs at the top are independent measurements. Vendor numbers and independent numbers come from different harnesses, so they are shown side by side, never mixed.

55Intelligence Index score: 4th of all models
3 ptsbehind the leader, Claude Opus 5.5 (58)
67%Terminal-Bench 4.0: highest AA has measured
$2.11per index task, vs. $5.98 for Opus 5.5 (max)

Moonshot reports

vendor claims own harness, partly internal tests

BenchmarkK3.1 ProComparison
Terminal-Bench 4.065.7%vs. Claude Opus 5.5: 66.4%
BenchCAD with tools92.7%vs. Claude Opus 5.5: 96.2%
OfficeQA Pro v264.4vs. Claude Opus 5.5: 62.2
Kimi Hallu Bench Hard internal8.3%vs. Kimi K3: 23.4% (about −65%)

Artificial Analysis measured

independent highest reasoning setting per model

MeasurementK3.1 ProComparison
Terminal-Bench 4.067%vs. Claude Opus 5.5 (max): 60%
GDPval-AA1,846 Elovs. Claude Opus 5.5: 1,866
Humanity’s Last Exam52%vs. Claude Opus 5.5: 61%
AA-Omniscience hallucination rate44%vs. Kimi K3: 53% · Gemini 4 Argon: 15%

The 65% hallucination drop holds on Moonshot’s own stress test. On an independent knowledge test, the rate fell from 53% to 44%.Moonshot: the stress test rates “do not represent overall error rates in daily use.”

Sources: Moonshot AI, Kimi K3.1 Pro tech blog (23 Oct 2026) (left card, vendor charts); Artificial Analysis launch article (23 Oct 2026) and Artificial Analysis model page (data as of 24 Oct 2026) (KPIs and right card).
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A Smaller Gap at Lower Listed Cost

The results matter because they suggest a model from a Chinese AI company can compete near the top of a widely followed comparison, particularly on agentic coding tasks. If Moonshot releases the promised weights on schedule and under a usable licence, companies could test, adapt or host the model themselves instead of relying solely on a proprietary provider. That could increase competition over deployment options and pricing.

The qualification is central: a strong benchmark score does not establish that the model will perform equally well in every workplace, or that organisations can run it economically. The listed API price is lower than Opus 5.5’s, but Artificial Analysis’s task estimate is tied to its own test. And a model with 2.8 trillion total parameters would require substantial infrastructure for self-hosting. Until weights and licence terms are published, the open-deployment comparison remains prospective.

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From Kimi K3 to K3.1 Pro

K3.1 Pro is described in the source material as a more heavily post-trained version of Kimi K3. The launch comes amid a persistent gap between leading closed models and downloadable open-weight systems: in the Artificial Analysis comparison cited by the source, Xiaomi’s MiMo-V2.6-Pro scored 46.3 before K3.1 Pro’s launch, while Opus 5.5 scored 57.6. K3.1 Pro’s 55.1 score narrows that spread, but the evaluator’s open-weight description is conditional on publication of the weights.

Moonshot’s launch material also promotes work across games, 3D modelling and finance. It says the model can build projects in Unity, Unreal Engine and Godot, and generate parametric models using Blender and CAD tools. Those examples are vendor demonstrations and claims, not independent confirmation of general performance. On BenchCAD with tools, Moonshot reported 92.7%, compared with its cited 96.2% for Opus 5.5 and 95.9% for GPT-6 Astra.

Moonshot also attributed a roughly 65% reduction in claim-level hallucinations to an internal stress test, where the rate fell from 23.4% for K3 to 8.3% for K3.1 Pro. The company says that test was deliberately designed to provoke errors and does not represent everyday error rates. Artificial Analysis measured a smaller decline on its separate evaluation, from 53% to 44%. The two figures come from different tests and should not be treated as directly interchangeable.

“The internal hallucination test is “deliberately crafted” to provoke errors, and its rates “do not represent overall error rates in daily use.””

— Moonshot AI

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Weights, Licence and Real-World Results

The main unresolved issue is whether Moonshot will publish the weights by its stated November 4 target. No K3.1 Pro licence had been published in the source material, so the permissions for commercial use, modification and redistribution are not yet clear. Without both the weights and terms, users cannot confirm the model’s practical status as an open-weight alternative.

Benchmark results also offer only a partial view. The source does not provide enough detail to independently assess every Moonshot demo or internal result, including claims about full game projects, finance work and fewer hallucinations. Performance may vary by prompt, tool access and task; the cited evaluations do not establish outcomes across all such settings. It is also unclear what hardware and operating costs would be required to run the full model outside Moonshot’s services.

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November 4 Weight Release Target

The next test is whether Moonshot publishes K3.1 Pro’s weights by November 4 and what licence accompanies them. Those details will determine whether researchers and businesses can inspect, modify and deploy the model independently, and on what terms. Further third-party evaluations could then check whether the launch-day benchmark performance holds across additional tasks and deployment setups.

Until then, customers can use the model through Moonshot’s listed products and API, while treating its open-weight status as pending. The available evidence supports a strong benchmark showing and competitive listed API pricing; it does not yet settle the model’s licensing, self-hosting costs or performance in routine use.

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Key Questions

How did Kimi K3.1 Pro rank?

Artificial Analysis scored it 55.1 on its Intelligence Index, placing it fourth in the reported comparison as of October 24, 2026.

Is Kimi K3.1 Pro open weight now?

No. Moonshot had made it available through its apps and API, but the weights were promised for November 4. The source material says no K3.1 Pro licence had been published.

What does it cost to use through the API?

Artificial Analysis lists $2 per million input tokens and $10 per million output tokens. Its estimated $2.11 cost per Intelligence Index task applies to its benchmark method, not every use.

Is the 65% hallucination reduction independently verified?

No. That figure comes from Moonshot’s internal stress test. Artificial Analysis reported a smaller decline on its separate evaluation, from 53% for K3 to 44% for K3.1 Pro.

Can companies run it on their own hardware?

Not yet from the information available: the weights and licence had not been published. Artificial Analysis lists 2.8 trillion total parameters, and the source says self-hosting a model of that size would require substantial infrastructure.

Source: ThorstenMeyerAI.com

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