Kimi K2

Kimi K2 is a 1-trillion-parameter mixture-of-experts (MoE) foundation model developed by Moonshot AI, released and open-sourced on July 11, 2025 . With 32 billion active parameters, it was designed for stronger code generation and general agentic tasks, achieving state-of-the-art results among open-source models on SWE Bench Verified, Tau2, and AceBench benchmarks at launch . A September 2025 update (K2-0905) expanded its context window from 128K to 256K tokens and further improved coding capabilities . The model quickly gained adoption across developer tools including Cursor, Perplexity, Vercel, and Windsurf . Moonshot AI followed K2 with Kimi K2 Thinking in November 2025, adding native reasoning and tool-use capabilities, and then Kimi K2.5 in January 2026, which introduced multimodal "Coding with Vision" and Agent Swarm architecture .