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OpenKey

Nemotron 3 Ultra (free)

NVIDIAReleased Jun 4, 2026Free

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...

Try in playground
Context window
1M tokens
Max output
66K tokens
Input
text
Output
text
Tokenizer
Other
Released
Jun 4, 2026
Reasoning
optional

Pricing

Per 1M tokens. The provider price and our flat 3% fee are separate columns — what you pay is their sum.

Per 1M tokensProvider+ 3% feeYou pay
InputFreeFree
OutputFreeFree

Benchmarks

Artificial Analysis

Intelligence index
37.8
Coding index
49.3
Agentic index
27.4

Design Arena

CategoryEloWin rateRank
3Dmodels121343.6%#40
ASCII artmodels109335.8%#44
Codemodels117437%#60
Data vizmodels116738.7%#63
Game devmodels119539.3%#53
SVGmodels114038.6%#45
UI componentsmodels118038.7%#54
Websitesmodels114032.6%#76

Head-to-head preference voting. How we filter and rank

Supported parameters

  • include_reasoning
  • max_tokens
  • reasoning
  • seed
  • temperature
  • tool_choice
  • tools
  • top_p

Call it

OpenAI-compatible: point your SDK at api.openkey.ai/v1 and use model nvidia/nemotron-3-ultra-550b-a55b:free.

Code sample language
curl https://api.openkey.ai/v1/chat/completions \
  -H "Authorization: Bearer $OPENKEY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "nvidia/nemotron-3-ultra-550b-a55b:free",
    "messages": [{"role": "user", "content": "Hello"}]
  }'
import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.openkey.ai/v1",
    api_key=os.environ["OPENKEY_API_KEY"],
)

completion = client.chat.completions.create(
    model="nvidia/nemotron-3-ultra-550b-a55b:free",
    messages=[{"role": "user", "content": "Hello"}],
)
print(completion.choices[0].message.content)
import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.openkey.ai/v1",
  apiKey: process.env.OPENKEY_API_KEY,
});

const completion = await client.chat.completions.create({
  model: "nvidia/nemotron-3-ultra-550b-a55b:free",
  messages: [{ role: "user", content: "Hello" }],
});
console.log(completion.choices[0].message.content);

Questions

How much does Nemotron 3 Ultra (free) cost via API?
Nemotron 3 Ultra (free) is free through OpenKey while NVIDIA offers it at no charge. No fee applies to free models.
What is Nemotron 3 Ultra (free)'s context window?
Nemotron 3 Ultra (free) accepts up to 1M tokens of context and returns up to 66K tokens per request.
Is Nemotron 3 Ultra (free) OpenAI-compatible?
Yes. Send requests to OpenKey's /v1/chat/completions endpoint with model "nvidia/nemotron-3-ultra-550b-a55b:free" using any OpenAI SDK — only the base URL and API key change.
What inputs does Nemotron 3 Ultra (free) support?
Nemotron 3 Ultra (free) accepts text input and produces text output.

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