JetBrains has released Mellum2, an open 12B-parameter Mixture-of-Experts model optimized for low-latency text and code tasks. The model activates only a subset of its parameters per token, delivering more than twice the inference speed of similarly sized open models while remaining competitive on code, reasoning, science, and math benchmarks. JetBrains positions Mellum2 as a "focal" model for high-frequency operations such as routing, RAG pipelines, sub-agent tasks, and private self-hosted deployments.

JetBrains has released Mellum2, a 12-billion-parameter Mixture-of-Experts model optimized for efficient text-and-code tasks like routing, retrieval, and agent workflows. The open model delivers faster inference than similarly sized alternatives while specializing in software engineering applications. Mellum2 is designed as a focused component for production AI systems, prioritizing speed and deployability in latency-sensitive scenarios.