JetBrains Releases Open-Source Thinking Model Mellum 2.1 on Hugging Face

JetBrains has open-sourced Mellum 2.1, a 12B-parameter MoE coding model with about 2.5B active parameters. GGUF quantized versions are trending on Hugging Face, and MTP support has been submitted to llama.cpp via PR #30612.

2026-10-15 ~ 2026-10-16 · 2 related posts

• JetBrains' thinking MoE Mellum 2.1 (12B-A2.5B) GGUF trends on Hugging Face — JetBrains · 2026-10-15
• JetBrains ships Mellum2.1 open coding model with RL-heavy post-training; llama.cpp MTP support submitted — jacek2023 · 2026-10-16