LLM Reference

Mellum2 12B

Researched today

Last refreshed 2026-06-01. Next refresh: weekly.

Open SourceCodingRAGAgentsLong contextJSON / Tool use

Mellum2 12B has model metadata, but missing tracked provider pricing keeps it from being a default production pick.

Decision context: Coding task fit, 0 tracked provider routes, and research from 2026-06-01.

Use it for

  • Teams evaluating coding, rag, and agents
  • Workloads that can use a 131k context window

Do not use it for

  • Cost-sensitive launches that need sourced token pricing
  • Vision or document-understanding workloads
  • Teams that need a tracked hosted API route today

Cheapest output

-

No tracked output price

Provider routes

0

No provider route in seed

Quality / dollar

Unknown

No task benchmark coverage yet

Freshness

2026-06-01

Researched today

fresh

Top use-case fit

Coding

Included by capability and metadata signals in the decision map.

RAG

Included by capability and metadata signals in the decision map.

Agents

Included by capability and metadata signals in the decision map.

Provider price ladder

No tracked provider token pricing is available for this model yet.

Benchmark peer barsfor Coding

No task-mapped benchmark peers are available for this model yet.

Migration checks

No linked migration route is available for this model yet.

About

Mellum2 12B is JetBrains' open-weights mixture-of-experts model for software engineering workflows. It has 12B total parameters, activates about 2.5B parameters per token, and supports long-context coding, tool use, function calling, reasoning, and agentic assistance.

Mellum2 12B has a 131k-token context window.

Capabilities

ReasoningFunction CallingTool Use

Rankings

Specifications

FamilyMellum 2
Released2026-06-01
Parameters12B (2.5B active)
Context131k
ArchitectureMixture of Experts
Specializationcode
LicenseApache 2.0
Trainingpretrained
Fine-tuninginstruction_tuned

Created by

Developer tools company building code-specialized Mellum models.

Prague, Czech Republic
Founded 2000
Website