LocalClaw/LLM/Mellum2.1 12B-A2.5B Thinking
Open-weight MoE

Mellum2.1 12B-A2.5B Thinking

Use case: Coding assistant. Check the memory fit and choose a setup path below.

16 GB catalogue minimum16 GB RAMQ4_K_MCoding assistant
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Open on Hugging FaceFiles, licence and available downloadsOpen llama.cpp setupAdvanced option: opens the model filesUse with LocalClawOptional workspace after the model is installed

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Parameters
12B (2.5B active, MoE)
Minimum RAM
16 GB
Model size
8.1 GB
Quantization
Q4_K_M

About Mellum2.1 12B-A2.5B Thinking

Catalogue summary: Official JetBrains Apache 2.0 coding-reasoning MoE with 12B total parameters, about 2.5B active parameters, 131K context and official Q4_K_M GGUF for llama.cpp, Ollama and LM Studio-compatible local runtimes.

Mellum2.1 12B-A2.5B Thinking has a catalogue minimum of 16 GB RAM with Q4_K_M. Actual memory use and speed vary by context length, runtime, backend and system headroom.

Use mellum2.1-12b-a2.5b-thinking as the catalogue search term in a compatible runtime, and confirm the available format on the upstream repository before download.

Model sourcePublic GGUF repository (verified 2026-11-06): JetBrains/Mellum2.1-12B-A2.5B-Thinking-GGUFUpstream releasePaper or model cardLicence text
codereasoningagenticspeedlong-contextmoe

Install path

01
Check RAM fitMinimum 16 GB RAM. Start with the Q4_K_M quant.
02
Load the modelSearch mellum2.1-12b-a2.5b-thinking in LM Studio.
03
Try your workloadStart with a short prompt, check memory use and adjust context length before running longer tasks.

Catalogue record

  • Family: mellum
  • Parameters: 12B (2.5B active, MoE)
  • Recommended quantization: Q4_K_M
  • Catalogue minimum RAM: 16 GB
  • Catalogue model size: 8.1 GB
  • Tags: code, reasoning, agentic, speed, long-context, moe

Practical limits

  • Catalogue RAM is a minimum estimate, not a guarantee for every context length or runtime.
  • Speed and memory use vary by quantization, backend, context length and system headroom.
  • Verify architecture, licence and usage restrictions in the linked upstream material before deployment.

Reading the scores

LocalClaw /10 is an editorial catalogue rating. Community /5 comes from member reviews. Your machine fit is a separate memory and runtime assessment.

Capability profile

Repository catalogue ratings used by LocalClaw's editorial rubric. They are not a standardized third-party benchmark.

speed
8
quality
8
coding
9
reasoning
9

Technical notes

Developer
JetBrains Research
License
Apache 2.0
Context window
131,072 tokens
Architecture
Mixture-of-Experts coding and reasoning language model with 12.15B total parameters, about 2.5B active parameters per token, 64 experts per layer, eight activated experts and a 131,072-token context window.

This model fits these next steps

Hardware fit is based on LocalClaw's RAM tier, model size and quantization metadata. Always leave memory headroom for your OS and runtime.

Starter desktopMac mini M4 16GBPortable fitMacBook Air M4 16GBBest 16GB models16GB RAM guide

Related catalogue entries

Linked mechanically by family, shared tags and nearby RAM tier; this is not a quality ranking.

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Where to go next