NVIDIA / nvidia/nemotron-3-ultra-550b-a55b
Nemotron 3 Ultra 550B A55B - access through LLMTR
Nemotron 3 Ultra is NVIDIA's largest open-weight model (550B total, 55B active parameters). With a 1M-token context window it suits long-document analysis, multi-step reasoning, function calling, and agent workflows that need JSON output. It is offered free with a daily usage quota; once the quota is reached, requests are limited until the next day.
Technical specifications
| Canonical ID | nvidia/nemotron-3-ultra-550b-a55b |
|---|---|
| Provider | NVIDIA |
| Context window | 1,000,000 tokens |
| Operations | CHAT_COMPLETIONS |
| Modalities | text |
Pricing
An 8% platform margin applies to credit top-ups; model usage prices are not separately marked up.
| Operation | Metric | Unit | Price |
|---|---|---|---|
| CHAT_COMPLETIONS | INPUT_TEXT | PER_1M_TOKENS | Not available |
| CHAT_COMPLETIONS | OUTPUT_TEXT | PER_1M_TOKENS | Not available |
Example usage
With existing OpenAI SDK flows, change only the base URL and model identifier.
curl https://llmtr.com/v1/chat/completions -H "Authorization: Bearer llmtr-your_key" -H "Content-Type: application/json" -d '{"model":"nvidia/nemotron-3-ultra-550b-a55b","messages":[{"role":"user","content":"Hello"}]}'Guides about this model
- Atria-Dawn vs Atria-Dawn Preview: stable release or open preview - Both rows are called on LLMTR with the same API key through /v1/chat/completions; they offer a 524,288-token context, text-only input, json_schema and tool calling, and they are free until 31 October 2026, 23:59 (TRT). Atria-Dawn is the stable release; Atria-Dawn Preview is the preview whose weights are open under the MIT license.
- Reasoning and the daily token allowance on Shanghai AI Lab models - All five rows reason before answering by default, and reasoning tokens count toward both max_tokens and the daily token allowance. To turn reasoning off, send "reasoning": false or add :fast to the model id; reasoning_effort returns 400. The rows are free until 31 October 2026, 23:59 (TRT).
- Long-document extraction with Atria-Dawn and JSON Schema - Atria-Dawn can read a long document in one request and return fields that follow a strict JSON Schema, and it is free until 31 October 2026, 23:59 (TRT). Input, output and reasoning share the same context window and the same daily allowance; turning reasoning off for extraction saves tokens.
- Shanghai AI Lab models after 1 November 2026: migration guide - The five Shanghai AI Lab models are free until 31 October 2026, 23:59 (TRT); from 1 November 2026, 00:00, they return 410 model_retired and are not redirected. Scientific questions with images and image-reading agents move to Nemotron 3.5 Super VL or Qwen3.6 35B-A3B; long text-based agent work moves to Nemotron 3 Ultra, Agnes 2.5 Flash, DeepSeek V4.1 Flash or MiniMax M3.1 Flash.
- K2 Horizon vs DeepSeek V4 Pro, GLM-5.3, Nemotron 3 Ultra - All four models are called on LLMTR with the same API key through /v1/chat/completions. K2 Horizon is free until 5 November 2026, 23:59 (TRT) and reasons before every answer. The free option with no end date is Nemotron 3 Ultra. On the paid side, DeepSeek V4 Pro costs less than GLM-5.3 outside peak hours.
Related models
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- Nemotron 3.5 Super VL nvidia/nemotron-3.5-super-vl
- Nemotron 3 Ultra 550B A55B 262K nvidia/nemotron-3-ultra-550b-a55b-262k
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