Nemotron 3 Ultra + OpenCode
0 of 6 steps

Run Nemotron 3 Ultra as your coding assistant

Use NVIDIA's 550B model in your terminal through OpenCode. Free API, no GPU, no credit card.

About 15 minutes Beginner friendly Windows, macOS, Linux Tested on Windows 11 and macOS

Before you start

Have these ready:

PrivacyNVIDIA logs free-tier usage. Do not send confidential code or personal data.
1

Check Node.js and Python

Confirm both tools are installed.

  1. Open PowerShell (Start menu, type PowerShell).
  2. Open Terminal.
  3. Run both commands:
node -v
python --version
node -v
python3 --version
PowerShell showing node and python versions
Both commands print a version number.
It worked ifYou see a version for each, for example v22.x and Python 3.x.
✅ Do
  • Install the LTS version of Node.js
  • Tick "Add Python to PATH" in the Python installer
❌ Don't
  • Continue if either command says "not recognized"
2

Install OpenCode

Install the terminal app that talks to the model.

npm i -g opencode-ai
opencode --version
OpenCode installed and version shown
OpenCode installed and printing its version.
It worked ifopencode --version prints a number such as 1.18.35.
OptionalThe setup script in step 4 also installs OpenCode. Doing it here just confirms npm works.
3

Get your free NVIDIA API key

Create the key that lets OpenCode use the model.

  1. Go to build.nvidia.com and sign in (create a free account if needed).
  2. In the search box, type nemotron-3-ultra-550b-a55b and open nvidia/nemotron-3-ultra-550b-a55b.
Searching for nemotron-3-ultra-550b-a55b on build.nvidia.com
Search for the model on the build.nvidia.com home page.
  1. On the Build tab, click Generate API Key.
  2. Copy the full key. It starts with nvapi-.
Model page with Generate API Key button
The Generate API Key button is at the top right of the code box. Key blurred.
✅ Do
  • Copy the whole key, including nvapi-
  • Keep it somewhere private
❌ Don't
  • Share the key or post it in screenshots
  • Paste it into any file you commit
4

Download the repo and run the setup

One script installs OpenCode, saves your key, and writes the config.

Download

git clone https://github.com/Aj-Networks/nemotron-3-ultra.git
cd nemotron-3-ultra

No git? Use Download ZIP, extract it, and open the folder in your terminal.

Run the setup

powershell -ExecutionPolicy Bypass -File .\scripts\setup-windows.ps1 -ProjectName my-project
chmod +x scripts/setup-unix.sh
./scripts/setup-unix.sh my-project

When asked, paste your API key and press Enter.

Setup script installing OpenCode and asking for the API key
The script installs OpenCode, then asks for your key.
✅ Do
  • Use PowerShell
  • Close and reopen the terminal after setup so the key loads
❌ Don't
  • Run it in Git Bash or CMD. It will fail with "command not found".
  • Skip reopening the terminal
5

Verify everything

Run all checks without opening OpenCode.

  1. Open a new terminal.
  2. Go to the repo folder, then run the checks:
cd path\to\nemotron-3-ultra
python scripts/opencode_runner.py my-project --verify-only
cd path/to/nemotron-3-ultra
python3 scripts/opencode_runner.py my-project --verify-only
All Phase 1 to 3 checks passing
Phase 1 checks your setup, Phase 2 loads your memory into OpenCode, Phase 3 self-tests the reply checker.
It worked ifEvery line says PASS and the last line says All phases complete.
New terminal, new folderEvery new terminal starts in your home folder. Always cd into the repo first.
6

Start coding

Launch OpenCode with Nemotron 3 Ultra.

python scripts/opencode_runner.py my-project
python3 scripts/opencode_runner.py my-project
  1. Check the bottom bar shows Nemotron 3 Ultra. If not, type /models inside OpenCode and pick it.
  2. Try a first prompt:
explain what this repo does in 3 bullet points
OpenCode answering a prompt with Nemotron 3 Ultra
Nemotron 3 Ultra answering inside OpenCode. The cost shown ($0.03) is OpenCode's own estimate. NVIDIA's free tier does not charge you.
✅ Do
  • Type / commands inside OpenCode, not in the terminal
  • Exit with Ctrl+C or /exit
❌ Don't
  • Send passwords, keys, or private data
  • Fire many requests at once (free tier limit is about 10 to 20 per minute)

Troubleshooting

ProblemFix
command not found for a .ps1 scriptYou are in Git Bash. Open PowerShell and use the step 4 command.
can't open file ... scripts\...Wrong folder. cd into the repo first.
opencode is not recognizedClose and reopen the terminal.
401 UnauthorizedKey not loaded. Reopen the terminal, or rerun the setup.
403 ForbiddenKey invalid or revoked. Generate a new one (step 3).
429 Too Many RequestsFree tier limit reached. Wait a few minutes.
/models not recognizedYou typed it in the terminal. Start OpenCode first (step 6).

More in the full troubleshooting guide.

You're set up

Nemotron 3 Ultra is now your coding assistant. Next time, just run step 6.