JetBrains/Mellum2.1-12B-A2.5B-Thinking
text-generation model by JetBrains
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Model card & documentation
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Mellum2.1 is the next version of Mellum2 Thinking. The architecture is unchanged (a 12B mixture-of-experts model with 2.5B active parameters), and almost all of the work for this version went into post-training, primarily reinforcement learning (RL): As a result, Mellum2.1 handles agentic tasks much better than Mellum2. After millions of sandboxed runs in real environments during training, it explores a codebase, edits files, and checks its own changes. Mellum2.1 Thinking has the following features: GGUF builds for llama.cpp, Ollama, and LM Studio,…
Read the full model card ↗ · Preview checked 2026-10-29T00:04:41.685Z
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Model overview
JetBrains/Mellum2.1-12B-A2.5B-Thinking is a text-generation model repository published by JetBrains on Hugging Face. The source reports the transformers library.
This page summarizes Hub metadata. For intended use, training data, evaluation results and limitations, consult the original model card.
Model facts
- Task
- text-generation
- Library
- transformers
- Recent downloads (30 days)
- 3,993
- Cumulative likes
- 169
- Hugging Face trending score
- 52
- Reported safetensors parameters
- 12,149,923,072
- Architecture
- MellumForCausalLM
- License
- apache-2.0
- Access
- Not gated by Hugging Face
- Created
- 2026-09-20T10:52:55.000Z
- Last modified
- 2026-10-07T23:08:12.000Z
Compatibility and lineage
Reported languages: en
Reported base models: JetBrains/Mellum2-12B-A2.5B-Base
Parameter count is not a RAM/VRAM requirement. Check precision, quantization, context length and runtime compatibility in the model card; no hardware or API-cost claim is inferred here.
Use and evaluate
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Source and freshness
Source: Hugging Face Hub. Metadata observed 2026-10-20T06:42:37.394Z. Daily imports are snapshots, not real-time monitoring.
Popularity and source listings do not establish security, suitability, licensing rights or benchmark performance.