Mellum 2 Models by JetBrains
1 model2026Up to 131k ctx
Last refreshed 2026-06-29. Next refresh: weekly.
Details
ResearcherJetBrains
LicenseApache 2.0OSI-approved
Commercial useCommercial use: permitted
Models1
Released2026
Max context131k
Capabilities
ReasoningAll models
JSON / Tool useAll models
About
Mellum 2 is JetBrains' 12B mixture-of-experts model family for software engineering workflows, with 2.5B active parameters per token and long-context support for coding, tool use, reasoning, and agentic work.
Decision facts
- Best fit
- codereasoningJSON / Tool use
- Capability starting point
- Mellum2 12B with 131k context and reasoning and JSON / Tool use
- Lowest tracked input
- Not tracked
- Closest related family
- Mellum
Current Variants
Use-when guidance is based on each model's tracked capabilities, context window, release date, and replacement status.
1 in view
Mellum2 12BCurrent
Use when the workload needs code, 131k context, and reasoning.
2026-06code131k contextreasoning
| Model | Use when | Released | Signals | Status |
|---|---|---|---|---|
| Mellum2 12B | Use when the workload needs code, 131k context, and reasoning. | 2026-06 | code131k contextreasoning | Current |
Release Timeline
1 release group2026-06
1 current
Mellum2 12B
Currentcode131k contextreasoning
Specifications(1 models)
| Model | Released | Context | Parameters | Reasoning | JSON / Tool use |
|---|---|---|---|---|---|
| Mellum2 12B | 2026-06 | 131k | 12B (2.5B active) | Yes | Yes |