Introducing Mellum2: A 12B Mixture-of-Experts Model by JetBrains

JetBrains has unveiled Mellum2, an open-weight large language model featuring a 12-billion parameter mixture-of-experts architecture. The release positions the software development company deeper into the generative AI landscape beyond its existing Copilot tools.

Mixture-of-experts designs allow models to activate specific sub-networks for different tasks, often improving efficiency compared to dense models of similar size. This approach aims to balance performance with computational costs for coding and reasoning applications.

By providing open weights, JetBrains enables developers to fine-tune and deploy the model locally. This move aligns with industry trends toward accessible, specialized models for software engineering workflows rather than relying solely on closed-source APIs.

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