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JetBrains·Jun 16, 2026·v2.0·open source

Mellum2

Mellum2 is a 12-billion-parameter AI model developed by JetBrains, designed to address challenges in production AI such as latency, throughput, and cost. It is specifically trained on natural language and code data, making it well-suited for tasks like routing, summarization, and intermediate reasoning in software engineering systems. Released under the Apache 2.0 license, Mellum2 offers a high-performance, cost-efficient alternative for AI infrastructure.

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overview

Mellum2 is a 12-billion-parameter AI model developed by JetBrains, designed to address challenges in production AI such as latency, throughput, and cost. It is specifically trained on natural language and code data, making it well-suited for tasks like routing, summarization, and intermediate reasoning in software engineering systems. Released under the Apache 2.0 license, Mellum2 offers a high-performance, cost-efficient alternative for AI infrastructure.

key features
  • 01Mixture-of-Experts (MoE) design with 12 billion total parameters, activating 2.5 billion per token for efficiency
  • 02Specialized training on natural language and code data for software engineering applications
  • 03High-throughput, low-latency inference suitable for real-time workloads
  • 04Open-sourced under the Apache 2.0 license for flexible deployment
  • 05Competitive performance in code generation, science, math, and reasoning benchmarks
  • 06Versatile tool for routing, summarization, and intermediate reasoning in AI workflows
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