Mellum2 12B
Mellum2 12B is a released coding, rag, and agents model with open-source and 131k context; evaluate it while provider pricing coverage matures.
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
- Family
- Mellum 2
- Released
- 2026-06-01
- Context
- 131k
- Parameters
- 12B (2.5B active)
- Architecture
- Mixture of Experts
- Specialization
- code
- Openness
- Open source
- License
- Apache 2.0OSI-approvedCommercial use: permitted
- Weights
- Available
- Code
- Unknown
- Training
- Pretrained
No tracked provider token pricing is available 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.
Top use-case fit: coding, agents, and build tasks
Coding
1 relevant benchmark in the decision map.
RAG
Included by capability and metadata signals in the decision map.
Agents
1 relevant benchmark in the decision map.
Provider price ladder
No tracked provider token pricing is available for this model yet.
Capabilities
Benchmark peer barsfor Coding
Benchmark scores(2)
| Benchmark | Score | Version | Evaluation | Source |
|---|---|---|---|---|
| Berkeley Function Calling Leaderboard v3 | 66.3 | BFCL v3 (accuracy%)Observed 2026-06-07 | — | Source |
| HumanEval | 78.4 | HumanEval (pass@1)Observed 2026-06-07 | — | Source |
Migration checks
No linked migration route is available for this model yet.
No tracked provider token pricing is available yet.