Nemotron vs. StableLM

Nemotron

Nemotron is NVIDIA's open model family for efficient reasoning, coding, long-context analysis, and agent orchestration. Nemotron 3 Ultra is the current flagship.

NVIDIA introduced the Nemotron 3 family in December 2025 with Nano, Super, and Ultra tiers. Nemotron 3 Ultra, released in June 2026, is a 550B-parameter hybrid Mamba-Transformer mixture-of-experts model with 55B active parameters and a one-million-token context window. It is optimized for long-running agent workflows, tool use, code, multilingual reasoning, and high-stakes retrieval. NVIDIA publishes the weights, training data, recipes, and fine-tuning workflows under the OpenMDW-1.1 license.

Further reading

• research.nvidia.com/labs/nemotron/Nemotron-3/
• developer.nvidia.com/blog/nvidia-nemotron-3-ultra-powers-faster-more-efficient-reasoning-for-long-running-agents/
• build.nvidia.com/nvidia/nemotron-3-ultra-550b-a55b/modelcard

StableLM

The StableLM series of language models is Stability AI's entry into the LLM space. Trained on The Pile, the initial release included 3B and 7B parameter models with larger models on the way.

Further reading

• news.ycombinator.com/item?id=35629127