NVIDIA

The company that sells the hardware gives away the parts of a model that are usually the secret. The card for nvidia/nemotron-3-ultra-550b-a55b — 550B total and 55B active, on a Mamba-2, mixture-of-experts and attention hybrid with multi-token predictionsource, accessed 2026-08-28 — says that "major portions of the pre-training corpus are released" as a public dataset collection, that major portions of the fine-tuning corpus are released too, and that the end-to-end training recipe is published in NVIDIA's developer repository. All ten of NVIDIA's rows in the OpenRouter catalog, as observed on 31 August 2026, carried a Hugging Face id, and no vendor with more rows than that published weights for all of them: the next fully-open listings belonged to meta-llama and MoonshotAI, tied at eight rows each.

The licence became a standard one as the models stopped being someone else's. NVIDIA's April 2025 reasoning release was a Llama derivative under the Nvidia Open Model Licensesource, accessed 2026-08-28; the Nemotron 3 family announced 15 December 2025 is NVIDIA's own hybrid architecture under the OpenMDW License Agreement, version 1.1source, accessed 2026-08-28, an off-the-shelf agreement rather than a house one. The exception is the interesting row. nvidia/nemotron-3.5-content-safety, the guardrail model that screens inputs and responses for other systems, is a fine-tune of Google's Gemma-3-4B-it, governed by OpenMDW plus the Gemma Terms of Use and Gemma Prohibited Use Policysource, accessed 2026-08-28. NVIDIA's safety model inherits a competitor's acceptable-use policy, and anyone deploying it to enforce policy is bound by Google's.

Then there are the rows that argue with each other. Five of the eighteen free listings in the catalog, as observed on 31 August 2026, were NVIDIA's — more than any other vendor — and two of them advertise a larger window than the paid row of the same model: nvidia/nemotron-3.5-lightning lists 262144tokensopenrouter-models, last checked 2026-09-14 while nvidia/nemotron-3.5-lightning:free lists 1000000tokensopenrouter-models, last checked 2026-09-14, a figure the public page repeats. Nemotron 3 Ultra does the same; nvidia/nemotron-3-super-120b-a12b runs the other way, its free row at 262144tokensopenrouter-models, last checked 2026-09-14 against the paid row's 262144tokensopenrouter-models, last checked 2026-09-14. And nvidia/nemotron-3-ultra-550b-a55b:batch heads higher than the row it batches on both input and output — not publishedlast known value, as of an unrecorded date — the source no longer lists this rowopenrouter-models, last checked 2026-09-14 against $0.60per million tokensopenrouter-models, last checked 2026-09-14 in, and not publishedlast known value, as of an unrecorded date — the source no longer lists this rowopenrouter-models, last checked 2026-09-14 against $2.40per million tokensopenrouter-models, last checked 2026-09-14 out, where the convention is a discount. Neither figure is necessarily NVIDIA's: each is the top listed provider's rate for its row, and two rows are not obliged to be headed by the same provider, so the inversion sits between two listings rather than being a surcharge anyone levied. It does come with a longer window: not publishedlast known value, as of an unrecorded date — the source no longer lists this rowopenrouter-models, last checked 2026-09-14 against 262144tokensopenrouter-models, last checked 2026-09-14.