Kimi K2 Thinking: The Leading Open-Weights Reasoning Model Now on Featherless.ai

We're thrilled to announce that Kimi K2 Thinking, MoonshotAI's groundbreaking reasoning model, is now available through Featherless.ai's serverless inference platform. This release marks a significant milestone in open-weights AI, delivering state-of-the-art performance on agentic tasks, coding, and complex reasoning benchmarks.

What is Kimi K2 Thinking?

Kimi K2 Thinking is the first reasoning variant in MoonshotAI's Kimi K2 model family, building upon the strong foundation of K2 Instruct models released earlier in 2025. With 1 trillion total parameters and 32 billion active parameters.

Breakthrough Performance Across All Benchmarks

K2 Thinking excels where it matters most: real-world agentic tasks that require long-horizon planning and adaptive reasoning. The model demonstrates a powerful ability to perform dynamic cycles of think → search → browse → code → think, continuously generating and refining hypotheses while verifying evidence and constructing coherent solutions. Key achievements include:

• State-of-the-art results on Humanity's Last Exam with tools, establishing new records in multi-domain expert-level reasoning

• More than double the human baseline on BrowseComp, demonstrating superior agentic search capabilities

• 71.3% on SWE-Bench Verified, showing exceptional coding abilities

• Executes 200 to 300 sequential tool calls without human interference, maintaining coherent reasoning across hundreds of steps

Beyond agentic tasks, K2 Thinking delivers impressive results across the full spectrum of AI capabilities. In mathematical reasoning, the model achieves 99.1% on AIME 2025 with Python tools and 95.1% on HMMT 2025 under the same conditions. On GPQA-Diamond, a benchmark testing graduate-level scientific knowledge, it scores 84.5%. In one remarkable demonstration, the model successfully solved a PhD-level mathematics problem involving hyperbolic space sampling through 23 interleaved reasoning and tool calls. The model also shows strong performance on component-heavy front-end tasks, can build complex applications from single prompts, and delivers enhanced creative and practical writing with deeper thematic resonance alongside more empathetic, balanced responses to personal questions.

Why This Matters

K2 Thinking represents a pivotal moment in AI development: an open-weights model competing directly with the most advanced closed-source systems from tech giants. On Humanity's Last Exam with tools, K2 Thinking scores 44.9%, surpassing GPT-5's 41.7% and significantly outperforming Claude Sonnet 4.5's 32.0%. On BrowseComp, it achieves 60.2% compared to GPT-5's 54.9% and Claude Sonnet 4.5's 24.1%, demonstrating superior agentic search capabilities.

What makes this achievement particularly remarkable is the resource efficiency. While companies like OpenAI and Anthropic invest billions of dollars in compute infrastructure and massive training runs, MoonshotAI has achieved comparable or superior performance with a fraction of those resources. This isn't just a technical accomplishment; it's a fundamental shift in what's possible for the broader AI community.

The implications extend far beyond benchmark numbers. When open-weights models match or exceed closed-source alternatives, developers gain unprecedented freedom. You can run these models on your own infrastructure, customize them for specific use cases, audit their behavior, and build applications without vendor lock-in or unpredictable API costs. The democratization of frontier-level AI capabilities means that innovation is no longer gated by access to proprietary systems.

Try K2 Thinking on Featherless.ai Today

For developers using Featherless.ai, this translates into practical advantages. You get GPT-5 class reasoning and Claude-level agentic capabilities through our flat-rate pricing model, eliminating the anxiety of per-token costs during development and experimentation. The open-weights nature of K2 Thinking means transparency in how the model operates, enabling you to make informed decisions about deployment and trust the systems you're building.

Kimi K2 Thinking is ready for immediate use through our serverless platform. Whether you're building applications that require deep reasoning, autonomous agent workflows, or complex coding tasks, our API provides seamless integration.

Get Started:

• Chat with K2 Thinking on Phoenix

• Integrate via the Featherless API

• Explore our documentation for implementation guides

Have questions about deploying K2 Thinking? Join us on Discord or check our documentation for API references and best practices.