Is Nemotron 3 Ultra available on FastMetal?

Not at the moment. GLM 5.3 Flash, from the same lab, is available on the FastMetal API today.

What is the context window of Nemotron 3 Ultra?

512,288 tokens, shared between the prompt and the response.

How does Nemotron 3 Ultra rank?

#105 on the public arena's Overall board (ELO 1,426). Ranks move as the leaderboard is updated.

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nvidia/nemotron-3-ultra-550b-a55b

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Nemotron 3 Ultra

NVIDIA Nemotron 3 Ultra is an open frontier-reasoning and orchestration model from NVIDIA, with 55B active parameters out of 550B total (MoE). Built on a hybrid Transformer-Mamba mixture-of-experts architecture, it...

6/4/2026

512,288 tokens

#70 Text (Math)

Specifications

Modalities

Input

text

Output

text

Supported Parameters

frequency_penalty

include_reasoning

logit_bias

max_tokens

min_p

presence_penalty

reasoning

reasoning_effort

repetition_penalty

response_format

seed

stop

structured_outputs

temperature

tool_choice

tools

top_k

top_p

Max Output Tokens

16,384

Reasoning Configuration

Default: Thinking on (effort: high)
Selectable effort levels: high
medium
Turning thinking off: Possible (reasoning.enabled: false)

How to control thinking, and what it costs

Frequently asked questions

Is Nemotron 3 Ultra available on FastMetal?: Not at the moment. GLM 5.3 Flash, from the same lab, is available on the FastMetal API today.
What is the context window of Nemotron 3 Ultra?: 512,288 tokens, shared between the prompt and the response.
How does Nemotron 3 Ultra rank?: #105 on the public arena's Overall board (ELO 1,426). Ranks move as the leaderboard is updated.