Install and Run Onyx Steam Uploader on Windows or Linux

Onyx ships as a single self-contained executable built with Godot Engine 4.5. There is no installer, package manager entry, or runtime dependency — download the binary and run it. This page covers prerequisites, platform-specific steps, and how Onyx stores its configuration.

Prerequisites

Before running Onyx, you need the following in place:

Steamworks SDK — Download from the Steamworks partner site. Onyx requires the ContentBuilder component, which includes SteamCMD.
ContentBuilder directory — The tools/ContentBuilder/ directory from the Steamworks SDK, with content/, output/, and scripts/ subdirectories present.
A Steamworks partner account — Required to authenticate with Steam and publish builds.

Onyx does not bundle SteamCMD. It calls the steamcmd.exe or steamcmd.sh binary that is already part of your ContentBuilder installation.

Download Onyx

Download the latest release from the Onyx GitHub Releases page. Choose the file that matches your platform:

Platform	File
Windows	`OnyxUploader.exe`
Linux	`OnyxUploader.x86_64`

Platform setup

Windows
Linux

Download the executable

Download OnyxUploader.exe from the releases page and place it in a folder of your choice. A dedicated folder is recommended because Onyx writes settings.cfg next to the executable.

C:\Tools\OnyxUploader\
└── OnyxUploader.exe

Run the executable

Double-click OnyxUploader.exe. No installer is needed — the application is a single self-contained file with all assets embedded.Windows SmartScreen may warn that the file is from an unknown publisher. Click More info then Run anyway to proceed.

Set your ContentBuilder path

On first launch, Onyx opens a setup dialog. Click Browse and navigate to your ContentBuilder directory (for example, C:\SteamworksSDK\tools\ContentBuilder). Onyx validates that content\, output\, and scripts\ subdirectories are present before saving the path.

SteamCMD on Windows is located at builder\steamcmd.exe inside the ContentBuilder directory. Onyx resolves this path automatically.

Download the executable

Download OnyxUploader.x86_64 from the releases page and place it in a directory of your choice.

mkdir -p ~/tools/onyx
mv OnyxUploader.x86_64 ~/tools/onyx/

Mark the file as executable

The downloaded file may not have the executable bit set. Run the following command before launching:

chmod +x ~/tools/onyx/OnyxUploader.x86_64

Run the executable

Launch Onyx from the terminal or your file manager:

~/tools/onyx/OnyxUploader.x86_64

Running from the terminal lets you see any startup output, which can help diagnose display or library issues.

Set your ContentBuilder path

On first launch, Onyx opens a setup dialog. Click Browse and navigate to your ContentBuilder directory. Onyx validates that content/, output/, and scripts/ subdirectories are present before saving the path.

SteamCMD on Linux is located at builder_linux/steamcmd.sh inside the ContentBuilder directory. Onyx resolves this path automatically.

ContentBuilder directory structure

Onyx validates the ContentBuilder directory when you configure it. The directory must contain the following structure:

ContentBuilder/
├── builder/               # Windows: contains steamcmd.exe
│   └── steamcmd.exe
├── builder_linux/         # Linux: contains steamcmd.sh
│   └── steamcmd.sh
├── content/               # Required — place your game files here
├── output/                # Required — SteamCMD writes upload logs here
└── scripts/               # Required — VDF build config files go here
    ├── app_<APPID>.vdf
    └── depot_<DEPOTID>.vdf

If any of content/, output/, or scripts/ are missing, Onyx will reject the directory and display an error. Create the missing folders manually before retrying.

Settings file

Onyx saves all configuration — including the ContentBuilder path and stored Steam accounts — to a file called settings.cfg.

Context	Location
Running the distributed executable	Next to `OnyxUploader.exe` or `OnyxUploader.x86_64`
Running from the Godot editor	`user://settings.cfg` (Godot’s user data directory)

To reset Onyx to a clean state, delete settings.cfg and relaunch. Onyx will open the setup dialog again on next startup.

Steam credentials stored in settings.cfg are saved in plain text. Keep the file and the directory containing Onyx in a location only you can access.

Get Started

Using the App

Reference

Install and Run Onyx Steam Uploader on Windows or Linux

Prerequisites

Download Onyx

Platform setup

ContentBuilder directory structure

Settings file

Next steps

Quickstart

Setting up ContentBuilder

​Prerequisites

​Download Onyx

​Platform setup

​ContentBuilder directory structure

​Settings file

​Next steps

Quickstart

Setting up ContentBuilder

Prerequisites

Download Onyx

Platform setup

ContentBuilder directory structure

Settings file

Next steps