# Mellum2.1 Gets to Work: A Fast Open Model for Coding Agents

DevFeed: [Mellum2.1 Gets to Work: A Fast Open Model for Coding Agents](<https://devfeed.tech/articles/mellum2-1-gets-to-work-a-fast-open-model-for-coding-agents-77378.md>)

Original publisher: [Read original article](<https://blog.jetbrains.com/ai/2026/10/mellum2-1-gets-to-work-a-fast-open-model-for-coding-agents/>)

Author: Bulat Salimzianov

Published: 2026-10-08T12:00:00Z

Content type: release

Language: en

Sources: [JetBrains](<https://devfeed.tech/sources/the-jetbrains-blog.md>)

Topics: [mixtral](<https://devfeed.tech/topics/mixtral.md>), [agentic-coding](<https://devfeed.tech/topics/agentic-coding.md>), [Reinforcement learning](<https://devfeed.tech/topics/reinforcement-learning.md>), [Large Language Model](<https://devfeed.tech/topics/llm.md>), [Open Source](<https://devfeed.tech/topics/open-source.md>)

Tags: [ai](<https://devfeed.tech/tags/ai.md>), [apache](<https://devfeed.tech/tags/apache.md>), [coding-agents](<https://devfeed.tech/tags/coding-agents.md>), [evaluation](<https://devfeed.tech/tags/evaluation.md>), [hardware](<https://devfeed.tech/tags/hardware.md>), [mellum](<https://devfeed.tech/tags/mellum.md>), [news](<https://devfeed.tech/tags/news.md>), [open-source](<https://devfeed.tech/tags/open-source.md>), [releases](<https://devfeed.tech/tags/releases.md>)

## AI overview

JetBrains released Mellum2.1, an open 12B mixture-of-experts model with 2.5B active parameters, trained with reinforcement learning in real environments for coding agents and sub-agents. The release reports improved agentic coding performance and faster inference, and describes local or self-hosted deployment options.

## Source excerpt

Trained with reinforcement learning in real environments, Mellum2.1 is built for coding agents and fast sub-agents that run on your own hardware. Today, we're releasing Mellum2.1, the next version of the 12B mixture-of-experts model we open-sourced in June. The architecture hasn't changed since version 2: it's still a compact, fast model with 2.5B active parameters, [...]