Kimi has released its latest open-weight model, K3, which is built on a mixture-of-experts architecture with 896 experts and 2.8 trillion parameters. The model features a one-million-token context window and is designed for complex reasoning tasks. Kimi claims that K3 performs on par with leading proprietary models in its own benchmarks, though it trails behind Claude Fable 5 and GPT-5.6 Sol. According to Kimi, the new model is the first open model in the roughly 3 trillion parameter range, with full weights set to be released by July 27. The model is aimed at long-running programming tasks, knowledge work, and complex reasoning. In Kimi's own benchmarks, K3 still trails the top proprietary models but beats every other system tested, including the Claude Opus models and Chinese rival GLM-5.2. All results were achieved at maximum or high thinking intensity, according to the company. Kimi K3 wins two out of six programming benchmarks and finishes second or third in the rest. Across all 35 tests, K3 took first place about seven times and landed second or third in most of the rest. Fable 5 won the most individual tests. In nearly every benchmark, K3 beat Opus 4.8, GPT 5.5, and GLM 5.2 by a wide margin. Depending on the benchmark, one of three agent systems was used: KimiCode, Claude Code, or Codex. That means the results weren't all collected under identical conditions.

Artificial Analysis confirmed K3's strong performance but noted a higher hallucination rate compared to its predecessor. The model scores 57 on the Artificial Analysis Intelligence Index, placing it on par with Opus 4.8 and GPT-5.5 but still behind Fable 5 and GPT-5.6 Sol. On agentic tasks, K3 reaches an Elo rating of 1,668 on GDPval v2, a significant jump from K2.6's 1,190. It beats GLM-5.2 (1,514), GPT-5.5 (1,494), and Claude Opus 4.8 (1,600), though it still falls short of Claude Fable 5 (1,760). K3 also takes the top spot on AutomationBench-AA, Artificial Analysis's version of Zapier's agentic SaaS workflow evaluation, with a score of 53 percent. On AA-Briefcase, a private long-horizon knowledge work evaluation, K3 reaches an overall Elo of 1,547, up 732 points from K2.6. Only Claude Fable 5 scores higher. Artificial Analysis calls K3 well-rounded, with rubric scoring and analytical quality close to Fable 5's level. GPT-5.6 Sol still leads on presentation quality, though. K3's accuracy rate improved from 33 percent to 46 percent on the AA-Omniscience Index, pushing the overall score from +6 to +18. But its hallucination rate climbed from 39 percent to 51 percent, meaning K3 fabricates more answers even as it gets more questions right.

Source: thedecoder