# Mellum2 Mellum2 is [[JetBrains]]' open-weight [[Large Language Models (LLMs)|LLM]] for AI workflows, released open source under [[Apache 2.0 License|Apache 2.0]] in June 2026. It is the successor to [[Mellum]]: where the original focused on code completion, Mellum2 handles both natural language and code. JetBrains positions it as engineered for the hard parts of production AI: latency, throughput, and cost. ## Architecture - 12B total parameters, [[AI Mixture of Experts (MoE)|MoE]] design with only ~2.5B active per token - Trained specifically on natural language and code; not multimodal - Open weights on HuggingFace ## What it's for A small, cheap, fast model to do the unglamorous plumbing of agentic systems rather than frontier reasoning: - Routing and orchestrating AI workloads - Low-latency RAG pipelines - Powering sub-agents in complex workflows - Private, local AI deployment ## References - https://blog.jetbrains.com/ai/2026/06/mellum2-goes-open-source-a-fast-model-for-ai-workflows/ - https://huggingface.co/collections/JetBrains/mellum-2 ## Related - [[Mellum]] - [[JetBrains]] - [[Junie (JetBrains)]] - [[Large Language Models (LLMs)]] - [[AI Open Weight Models]] - [[AI Mixture of Experts (MoE)]] - [[Apache 2.0 License]]