JetBrains releases Mellum2.1, a 12-billion-parameter open MoE coding model

Oct 8, 2026 · Issue 10 · 5 sources, 5 articles

JetBrains has released Mellum2.1, a 12-billion-parameter open MoE model for coding agents. According to Hungarian sources, it was trained on real codebases.

Who is affected and how

tech lead

As an open model it can run on your own infrastructure for coding agents, so it is worth comparing with closed models.

CTO

A smaller open model can reduce dependence on external providers.

Narrative: Open and Chinese models drive down prices

Sources

• JetBrains Releases Mellum2.1, a 12B Open MoE Model for Coding Agents | AI News Feedainewsfeed.tech · Oct 8, 2026
• JetBrains Releases Mellum2.1: A 12B MoE Open Model for Coding Agents - MarkTechPostmarktechpost.com · Oct 8, 2026
• JetBrains Mellum2.1: 12B Coding Model Hits 47% SWE-Benchshattered.io · Oct 9, 2026
• Mellum2.1: fast open model for coding agents | AI Newsaihirek.info · Oct 8, 2026 · magyar
• JetBrains' new generative AI model learned to work on real codebasesnice.hu · Oct 11, 2026 · magyar

Machine-generated summary based on the titles and excerpts of the source articles. The facts come from the linked article.