MiniMax Open-Sources M3.1-Flash: 428B Multimodal MoE with 1M Context

On October 23, MiniMax officially open-sourced MiniMax-M3.1-Flash and released its weights. The company confirmed that the model previously pre-trained anonymously under the codename "Space Bunny"—consuming 200T+ tokens—was in fact M3.1-Flash, an upgraded version of MiniMax-M3.

Confirmed

• The model is a natively multimodal MoE architecture with roughly 428B total parameters and 23B active parameters per token.
• It supports a 1 million-token context with sparse attention used throughout (the post mentions a Block-sparse style mechanism).
• It is positioned for coding, agentic workflows, and computer use; MiniMax says it excels at agentic tasks and safety.
• Weights are available on Hugging Face (MiniMaxAI/MiniMax-M3.1-Flash) and ModelScope.
• Ecosystem support: Together AI is a day-0 launch partner offering fully managed APIs; NVIDIA NeMo supports fine-tuning on up to 128 GPUs.

Not Yet Confirmed

• Reddit user @mrtime777 noted that the post lacks benchmark data and details; the model's actual performance and pricing remain to be announced.

Why It Matters

This is another large open-source multimodal MoE model, pre-trained anonymously (as "Space Bunny") on 200T+ tokens. The combination of ultra-long context, native sparse attention, and an Agent/computer use focus shows open-source models are now targeting frontier use cases like tool calling and automated workflows, while day-0 ecosystem support from Together and NVIDIA lowers the barrier to adoption.

2026-10-23 ~ 2026-10-23 · 8 related posts

Full story(3 episodes)→

• Episode 1: MiniMax-M3.1-Flash scores Intelligence Index 42, ranks 4th but shows 93% hallucination rate in AA evals(2026-10-19, 9 posts)
• Episode 2: MiniMax Open-Sources M3.1-Flash: 428B Multimodal MoE with 1M Context(2026-10-23, 8 posts)
• Episode 3: vLLM Announces Day-0 Support for MiniMax M3.1 Flash with NVFP4 Gains(2026-10-23, 4 posts)

• [source] MiniMax Quietly Lists New M3.1-Flash Model on Hugging Face — mrtime777 · 2026-10-23
• [source] MiniMax-M3.1-Flash goes open weights with day-0 NVIDIA NeMo fine-tuning up to 128 GPUs — MiniMax_AI · 2026-10-23
• MiniMax open-sources M3.1 Flash: 428B total params, 23B active, built for agentic tasks — VoidAsuka · 2026-10-23
• MiniMax ships M3.1 Flash: native multimodal MoE with 1M context and sparse attention throughout — KyeGomezB · 2026-10-23
• [source] MiniMax open-sources M3.1 Flash: 428B MoE with 23B active, 1M context, live on Together AI — MiniMax_AI · 2026-10-23
• MiniMax Open-Sources M3.1 Flash: 428B Params, 23B Active, NVIDIA Vera Rubin Day-0 Support — NVIDIAAI · 2026-10-23
• MiniMax M3.1 Flash ships with day-0 vLLM support and NVFP4 serving stack — woosuk_k · 2026-10-23
• MiniMax site lists wave of new releases: M3.1 Flash, M3, video model H3, Speech 2.8 and more — lipeng0820 · 2026-10-23