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JetBrains has open-sourced Mellum 2, a 12B-parameter coding model that uses an MoE design to deliver fast agentic AI workflows.
Jun 1, 2026 22:26 EDT
JetBrains has announced that it is open-sourcing its new machine learning model designed for software engineering systems, Mellum2.
This comes a little over a year after the company open-sourced the original Mellum in 2025, a relatively small model with 4 billion parameters. Mellum2, its successor, comes with 12B parameters in total, though JetBrains promises that it keeps computation fast by utilizing only 2.5B active parameters per token. The engineering team deployed a sparse Mixture-of-Experts framework to achieve these fast inference speeds on standard hardware.
