open source

Chinese company Moonshot AI released Kimi K3, an open source model that the company claims demonstrates frontier-level performance while trailing only Claude Fable 5 and GPT 5.6 Sol. Independent analyses from Arena.ai and Vals AI suggest the model is competitive with flagship frontier models, reigniting debate about Chinese AI capabilities and open source model development.

Mistral AI released Leanstral 1.5, a free Apache-2.0 licensed model with 119B total parameters and 6B active parameters specialized for formal verification in Lean 4. The model achieves 100% on miniF2F benchmark, solves 587 of 672 PutnamBench problems at $4 per problem (versus $300+ for competitors), and reaches state-of-the-art 87% on FATE-H and 34% on FATE-X benchmarks.

Microsoft is evaluating a self-hosted version of DeepSeek V3 to power Copilot Cowork as agent costs spiral. The company plans to launch a lower-cost tier within weeks while moving to usage-based pricing, charging enterprises for actual compute consumed rather than flat fees.

Cohere Labs has released North Mini Code 1.0, a 30B-parameter sparse Mixture-of-Experts model with 3B active parameters and a 256K context window. The Apache 2.0-licensed model is optimized for agentic software engineering, featuring 128 experts with 8 activated per token, and trained specifically for tool use in coding tasks.

NVIDIA has released Nemotron 3.5 Content Safety, a 4B-parameter model built on Google Gemma 3 4B IT that provides multimodal safety classification across approximately 140 languages. The model includes a 128K context window, custom enterprise policy enforcement, auditable reasoning traces, and is releasing its training dataset.

JetBrains has released Mellum2, a 12-billion parameter Mixture-of-Experts model that activates only 2.5 billion parameters per token. The open-source model is designed for code generation, RAG pipelines, and agent workflows with 2x faster inference than similar-sized models.

Arcee AI has released Trinity Large Thinking, an open source reasoning model with a 262,144-token context window. The model is available free via OpenRouter and claims strong performance in PinchBench, agentic workloads, and reasoning tasks.

Moonshot AI has released Kimi K2.6, an open-source multimodal model with 1 trillion total parameters (32B activated) and 256K context window. The model achieves 80.2% on SWE-Bench Verified, 58.6% on SWE-Bench Pro, and supports horizontal scaling to 300 sub-agents executing 4,000 coordinated steps.