Do I need a local GPU to run Nemotron 3 Ultra 550B?

No. Running a 550B parameter model locally requires 4x B200 GPUs. Instead, NVIDIA hosts the model and provides free API access, while you run the lightweight OpenCode CLI client locally on Windows or Mac.

How much does the NVIDIA Nemotron 3 Ultra API cost?

NVIDIA provides free API access via NVIDIA Build (build.nvidia.com) with 1M token context window support.

NEMOTRON_3_ULTRA.exe

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Run Nemotron 3 Ultra in Your Terminal ⚡

NVIDIA's 550B open reasoning model, wired into OpenCode as your autonomous terminal coding agent. No GPU. No subscription. Copy, paste, done.

⚡ TL;DR

Cloud Power, Local Speed: Run NVIDIA's 550B Nemotron 3 Ultra via free hosted cloud API while OpenCode runs locally in your terminal.
No Enterprise Hardware Required: Zero GPU overhead on your local laptop; all heavy reasoning and inference compute runs on NVIDIA infrastructure.
Massive 1M Context Window: Ingest entire code repositories and complex multi-file projects without context truncation.
Autonomous Coding Agents: Hybrid Mamba-Transformer MoE architecture delivers superior agentic planning and syntax debugging.
Drop-In Claude Code Alternative: Compatible with OpenAI/Claude terminal CLI workflows for seamless developer ergonomics.

MODEL SPECIFICATIONS & BENCHMARKS

PARAMETERS

550B Total

55B active per token

CONTEXT WINDOW

1,000,000 Tokens

Full repo ingestion

ARCHITECTURE

Hybrid MoE

Mamba-Transformer

API COST

Free Tier

Via NVIDIA Build

STEP 01

Install OpenCode CLI

Select the installation method for your operating system:

🪟 Windows Setup (PowerShell / Windows Terminal)

Option A — winget (Recommended for Windows 11 & updated Windows 10):

POWERSHELL

winget install SST.opencode

Option B — npm (Node.js LTS):

NPM

npm install -g opencode-ai@latest

Option C — Scoop:

SCOOP

scoop bucket add extras; scoop install extras/opencode

💡 Tip: Use Windows Terminal rather than legacy cmd.exe for full ANSI color and interactive terminal rendering.

🍎 macOS Setup (Terminal / iTerm2)

CURL_OR_BREW

curl -fsSL https://opencode.ai/install.sh | bash

STEP 02

Verify Installation

Close your terminal and open a brand new window so PATH variables refresh. Run:

VERIFY_CLI

opencode --version

If PowerShell gives an execution policy error on Windows, run this one-time fix: Set-ExecutionPolicy -Scope CurrentUser RemoteSigned

STEP 03

Get Your Free NVIDIA API Key

Visit build.nvidia.com/settings/api-keys or explore the Nemotron 3 Ultra Model Page.
Sign in or sign up with your personal email (e.g. Gmail).
Navigate to Settings → API Keys → Generate API Key.
Copy the key immediately (starts with nvapi-). It is displayed only once.

⚠️ Note on Permissions: If you see "No API Key Permissions", you are signed in under an SSO company organization. Click the green Switch Org button and select your personal default org.

STEP 04 & 05

Connect NVIDIA & Launch Nemotron

Move into any project directory and launch OpenCode:

LAUNCH_AGENT

cd $HOME/Desktop/my-project
opencode

Inside the interactive OpenCode terminal screen, run the following slash commands:

1. Connect Provider:

/connect

Select NVIDIA from the list, paste your nvapi- key, and press Enter.

2. Set Nemotron 3 Ultra Model:

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

Now ask it: "Read this codebase and explain what the system does." It will read files, write code, run commands, and debug errors autonomously.

STEP 06

Direct Python Scripting (OpenAI-Compatible)

If you want to call Nemotron 3 Ultra directly in your Python pipelines, use the OpenAI client with NVIDIA's base URL:

PYTHON_NEMOTRON

import os
from openai import OpenAI

client = OpenAI(
    base_url="https://integrate.api.nvidia.com/v1",
    api_key=os.environ["NVIDIA_API_KEY"],
)

stream = client.chat.completions.create(
    model="nvidia/nemotron-3-ultra-550b-a55b",
    messages=[
        {"role": "user", "content": "Write a Python script that renames every file in a folder to lowercase."}
    ],
    temperature=1,
    top_p=0.95,
    max_tokens=16384,
    extra_body={"chat_template_kwargs": {"enable_thinking": True}},
    stream=True,
)

for chunk in stream:
    if chunk.choices and chunk.choices[0].delta.content:
        print(chunk.choices[0].delta.content, end="")

TROUBLESHOOTING

Common Issues & Instant Fixes

SYMPTOM	RESOLUTION
'opencode' not recognized	Open a fresh terminal window to reload PATH. If still failing, install via npm.
running scripts is disabled	Run `Set-ExecutionPolicy -Scope CurrentUser RemoteSigned` in PowerShell.
401 Unauthorized	API key is invalid, expired, or has a leading/trailing space. Generate a fresh key.
No API Key Permissions	Wrong organisation selected. Click Switch Org → personal default org.
Nemotron not in /models	Provider is not connected. Run `/connect` again and select NVIDIA.
Replies feel deliberate / slow	Nemotron 3 Ultra is an open reasoning model—it outputs chain-of-thought before code.

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