A side-by-side comparison of release history, capabilities, licensing and model sizes.
| Attribute |
 GPT-J
|
Nemotron |
|---|---|---|
| Developer | EleutherAI | NVIDIA |
| Current generation | – | Nemotron 3 Ultra |
| Initial release | 2021-06-09 | 2025-12-15 |
| Instruct tuned | Yes | Yes |
| Coding | No | Yes |
| Finetuning | Yes | Yes |
| Open source | Yes | Yes |
| License | Apache 2.0 | OpenMDW-1.1 |
| Model sizes | 6B | 550B (55B active) |
| Links |
GPT-J is a model released by EleutherAI shortly after its release of GPTNeo, with the aim of delveoping an open source model with capabilities similar to OpenAI's GPT-3 model. With a larger size than GPTNeo, GPT-J also performs better on various benchmarks.
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.
