Nemotron 3 Ultra 550B

Overview

Nemotron 3 Ultra 550B is a 550B parameter mixture-of-experts architecture with 55B active parameters per forward pass. It combines a hybrid Mamba-Transformer design to handle reasoning, coding, and general-purpose text tasks efficiently. On Kyma, the model runs through an OpenAI-compatible endpoint with automatic request failover and exact cost reporting in the response payload. It supports tool use, structured outputs, and prompt caching, which bills repeated prefixes at this model’s cached input rate. The model accepts a 1,000,000 token context window but caps generation at 32,768 output tokens. It is strictly text-only and does not support vision or multimodal inputs.

Specs

Field	Value
Model ID	`nemotron-3-ultra-550b`
Best for	Reasoning, coding, general, long context, fast throughput
Context window	1M
Max output tokens	33K
Input modalities	Text
Output modalities	Text
Tool calling	Yes
Structured outputs	Yes
Prompt caching	Yes
Speed	Fast
Cost band	Balanced
Release stage	Stable

Pricing

	Per 1M tokens
Input	$0.68
Output	$3.38

Use this when

Long Context Document Analysis — Process large technical manuals or codebases within the one million token window.
Automated Code Generation — Generate and refactor code using built-in reasoning and tool-use capabilities.
High Throughput Chat — Handle conversational workloads that require fast text generation and structured JSON outputs.
Reasoning Heavy Workflows — Execute multi-step logical tasks where active parameter routing improves accuracy.

Not ideal for

Tasks requiring image or video understanding, or workloads that need output sequences longer than 32,768 tokens.

Pick something else when

You need vision or multimodal inputs: use gemini-3.5-flash or gpt-5.6-terra.
You require output sequences longer than 32k tokens: use qwen-3.7-max or deepseek-v4-pro.
You need maximum raw speed for simple completions: use qwen3.7-flash or gemini-3.6-flash.

Example

from openai import OpenAI

client = OpenAI(base_url="https://kymaapi.com/v1", api_key="ky-...")

response = client.chat.completions.create(
    model="nemotron-3-ultra-550b",
    messages=[{"role": "user", "content": "..."}],
    tools=[...],  # function calling supported
)

Agent query example

Ask the API which models fit, instead of hardcoding an id:

curl "https://kymaapi.com/v1/models?recommended_for=write-code&tools=true&quality_tier=frontier-open"

FAQ

Does this model support image inputs? No, it is strictly text-only for both input and output modalities. How does prompt caching work with this model? Repeated prompt prefixes are billed at this model’s cached input rate, reducing costs for long-context or system-prompt-heavy workflows. Can I use function calling and structured outputs? Yes, the model natively supports tool use and structured JSON responses, which are routed through Kyma’s OpenAI-compatible API.

​Overview

​Specs

​Pricing

​Use this when

​Not ideal for

​Pick something else when

​Example

​Agent query example

​FAQ