Open-source AI · October 2026
Kimi K3.1 Pro puts open-source AI a month behind the best
The best open model used to trail the best closed one by about three months. Kimi’s new model cuts that to 31 days, and keeps a Chinese lab at the top of open-source AI for the 765th day in a row.
On 23 Oct, Kimi released K3.1 Pro. It scores 55.1 on the Artificial Analysis Intelligence Index, a blend of hard tests in reasoning, knowledge, coding and agent work. That is 2.5 points short of Claude Opus 5.5, the best model of any kind, and 8.8 points above the previous best open model, Xiaomi’s MiMo-V2.6-Pro. Kimi says the weights will be free to download by 4 Nov; until then it runs on Kimi’s own API.
In time, that puts open-source AI about a month behind: Claude Opus 5.5 first scored that high 31 days earlier. When Xiaomi released MiMo-V2.6-Pro in September, the gap was 104 days (we wrote about it earlier this month). Only Claude Opus 5.5 (57.6), Claude Sonnet 5.5 (56) and Muse Wonder Full (55.8) score higher today.
The closest one with a public API price is Claude Sonnet 5.5, Anthropic’s mid-sized model, at its highest effort setting. Kimi’s new model scores 0.9 points less and has the same list price: $2 per million input tokens and $10 per million output tokens. It is, in effect, an open-source Sonnet 5.5: once the weights are out, anyone can run it.
Artificial Analysis Intelligence Index (current version) of the best model released by each date, closed and open-weights. No open model has ever had the top score; the shading is the closed lead. Hover or tap for the models.
That the new leader is Chinese is not news. A Chinese lab has had the best open model every day since 19 Sep 2024, when Alibaba’s Qwen2.5 Instruct 72B passed Meta’s Llama 3.1: 765 days in a row. In 2023, open source meant Llama. Press play to watch the chart turn over.
Kimi, 55.1
Open-weights models only. The best score among open models each lab had released by that date, since Llama 2 (18 Jul 2023), on the Artificial Analysis Intelligence Index (current version, highest effort setting). The axis rescales as scores rise; the top 10 labs are shown.
Six labs, one country
The lead doesn’t belong to one company. Alibaba, DeepSeek, Kimi, Z.ai, MiniMax and Xiaomi have each held it. DeepSeek had it longest, 307 days in total, most of it with R1, the reasoning model that briefly knocked Nvidia’s share price in January 2025. Z.ai, the lab behind GLM, is second with 198. Since September 2025 there have been 14 different No. 1s, about one every 30 days, and none lasted more than 72 days.
Hover or tap a stretch to see the model.
The open-weights model with the highest Artificial Analysis Intelligence Index score among those released by each date, 1 Sep 2024 to 23 Oct 2026.
America is three months behind
On 15 Oct, Meta released Muse Spark Open, its first open model since Llama 4 in April 2025. It scores 38.9. A Chinese lab first beat that 91 days earlier, with Kimi K3. That makes it the best open model from anywhere outside China, ahead of South Korea’s Motif 3 (33.6).
It had been worse. In June 2026, the best non-Chinese open model was Google’s Gemma 4 26B A4B, a model small enough for a laptop, and it matched what China had released 246 days, or about eight months, earlier. OpenAI’s gpt-oss-120b, in August 2025, never topped this index.
Artificial Analysis Intelligence Index (current version) of the best open-weights model released by each date. Blue shading is China’s lead; orange, the 18 days in September 2024 when Meta’s Llama 3.1 Instruct 405B led. Hover or tap for the models.
Measured in time, the rest of the world’s best open model was a median of 109 days behind China’s in 2025 and 145.5 days this year. Meta’s release brings it back to about three months.
The best model you can own
Once Kimi K3.1 Pro’s weights are out, anyone can run it or serve it, which keeps prices down. For two years the best model you could own has come from China. It has never been this close to the best model you can rent.
Method
Intelligence scores are the Artificial Analysis Intelligence Index (current version), taking each model at its highest effort setting, by release date, as of 23 Oct 2026. Only models Artificial Analysis marks as open weights count. Our snapshot is from 18 October; we added Kimi K3.1 Pro, released on 23 Oct 2026 with an index score of 55.1, and count it as open because Kimi says it will publish the weights by 4 Nov 2026. Other models released after 18 October aren’t counted. A model counts from its release date. We count from September 2024 because before that every model scores between 5 and 9 on the current index, too close to rank. The race starts at Llama 2 on 18 Jul 2023 and shows each lab’s best open model on each date. Labs are placed by where they are based; a fine-tune counts for the lab that released it, wherever its base model came from.