Kit comes with a very rich and flexible configuration system based on Carbonite settings. Settings is a runtime representation of typical configuration formats (like json, toml, xml), and is basically a nested dictionary of values.

Quick Start

When you run a kit executable, it doesn’t load any kit app file:

> kit.exe

That will start kit and exit, without enabling any extensions or applying any configuration, except for the built-in config: kit-core.json.


To see all flags call > kit.exe -h

To see default kit settings pass --/app/printConfig=true:

> kit.exe --/app/printConfig=true

That will print all settings. This syntax --/ is used to apply settings from the command line. Any setting can be modified in this way. You may notice that the config it printed includes app/printConfig. You can try adding your own settings to the command line and observing them in the printed config to prove yourself that it works as expected.

Another useful flag to learn early is -v to enable info logging or -vv to enable verbose logging. There are settings to control logging more precisely, but this is an easy way to get more logging in console and debug startup routine.

> kit.exe -v

To make kit do something let’s enable some extensions:

> kit.exe --enable omni.kit.window.script_editor

That enables a script editor extension. You may also notice that it enabled a few extensions that it depends on. You can stack multiple --enable keywords to enable more extensions.

You can also add more folders to search in more for extensions with --ext-folder:

> kit.exe --enable omni.kit.window.script_editor --ext-folder ./exts --enable

That enables you to create e.g exts/ and start hacking on your own extension right away.

Those flags, like --enable, --ext-folder and many others are just shorthand for commonly-used settings. For example, they just append to /app/exts/enabled and /app/exts/folders arrays respectively.

Application Config

Settings can also be applied by passing a configuration file as a positional argument to Kit:

> kit.exe my.toml

This kind of config file becomes the “Application config”. It receives special treatment from Kit:

  1. The config name becomes application name.

  2. Separate data, documents and cache folders are created for applications.

  3. The Folder where this config exists located becomes the application path.

This allows you to build separate applications with their own data and behavior.

Kit File

A Kit file is the recommended way to configure applications.

> kit.exe my.kit

Kit files are single-file extensions (basically renamed extension.toml files). Only the [settings] part of them is applied to settings (as with any extension). Here is an example:

title = "My Script Editor App"
version = "0.1.0"
keywords = ["app"]

"omni.kit.window.script_editor" = {}

[settings] = "123"

exts."omni.kit.window.script_editor".windowOpenByDefault = true

As with any extension, it can be named, versioned and even published to the registry. It defines dependencies in the same format to pull in additional extensions.

Notice that the setting windowOpenByDefault of the script editor extension is being overridden. Any extension can define its own settings and a guideline is to put them in the extension.toml file of the extension. Check the extension.toml file for omni.kit.window.script_editor. Another guideline is to use the root exts namespace and the name of extension next.

The goal of the .kit file is to bridge the gap between settings and extensions and have one file that the user can click to run Kit-based application (e.g. if .kit file extensions are associated with kit.exe in the OS).

System Configs

You can create system wide configuration files to override any setting. There are few places to put them:

  1. ${shared_documents}/user.toml - To override settings of any kit application in the shared documents folder, typically in (on Windows): C:\Users\[username]\Documents\Kit\shared\user.toml

  2. ${app_documents}/user.toml - To override settings of particular application in the application documents folder, typically in: C:\Users\[username]\Documents\Kit\apps\[app_name]\user.toml

  3. <app .kit file>\<0 or more levels above>\deps\user.toml - To override settings of any kit application locally, near the application .kit file. Only in portable mode.

  4. <app .kit file>\<0 or more levels above>\deps\[app_name]\user.toml - To override settings of particular application locally, near the application .kit file. Only in portable mode.

  5. ${shared_program_data}/kit.config.toml - To override settings of any kit application in the shared program data, typically in (on Windows): %PROGRAMDATA%/NVIDIA Corporation/Kit/kit.config.toml

  6. ${app_program_data}/kit.config.toml - To override settings of particular application in the application program data, typically in (on Windows): %PROGRAMDATA%/NVIDIA Corporation/Kit/[app name]/kit.config.toml

To find the path of these folders on your system, you can run Kit with info logging enabled and look for Applied configs: and Non-existent configs: messages at the beginning. Also, Look for Tokens: list in the log. For more info: Tokens.

Special Keys

Appending Arrays

When configs are merged, one value can override another. Sometimes we want to append values for arrays instead of override. For this, use the special ++ key. For example, to add additional extension folders to the /app/folders setting, you can write:

folders."++" = ["c:/temp"]

You can put that for instance in user.toml described above to add more extension folder search paths.

Importing Other Configs

You can use the @import@ key to import other config files in that location:

"@import@": ["./some.toml"],

That will import the config some.toml under the key foo. The ./ syntax implies a relative path, and that the config file is in the same folder.

Portable Mode

A regular kit-based app installation sets and uses system wide data, cache, logs folders. It also reads the global Omniverse config in a known system-specific location. To know which folders are being used, you can look at tokens, like ${data}, ${cache}, ${logs}. They can be found at the beginning of each log file.

Kit based apps can also run in a portable mode, using a specified folder as a root for all of those folders. Useful for developers. Local builds by default run in portable mode. There are a few different ways to run kit in portable mode:

Cmd Args

Pass --portable to run kit in portable mode and optionally pass --portable-root [path] to specify the location of the portable root.

Portable Configs (Markers)

Kit looks for the following configs that force it to run in portable mode. It reads the content of a file if it finds one, and treats it as a path. If a path is relative - it is relative to this config folder. The priority of search is:

  1. App portable config, e.g. foo.portable near foo.kit when run with: kit.exe foo.kit

  2. Kit portable config near experience, e.g. kit.portable near foo.kit when run with: kit.exe foo.kit

  3. Kit portable config near kit.exe, e.g. kit.portable near kit.exe

Changing Settings With Command Line

Any setting can be changed via command line using --/ prefix:

> kit.exe --/[path/to/setting]=[value]

Path to setting is separated by / and prefixed by --/.

For example, if the required option is ignoreUnsavedOnExit as shown in the printed JSON configuration:

<ISettings root>:
    "app": {
        "hangDetector": {
            "enabled": false,
            "timeout": 120
        "file": {
            "ignoreUnsavedOnExit": false,

To change the value of ignoreUnsavedOnExit to true, you need to add --/app/file/ignoreUnsavedOnExit=true to the command line:

> kit.exe --/app/file/ignoreUnsavedOnExit=true

To specify a boolean value, true and false strings must be used.


  1. The values are case-insensitive and using --/some/path/to/parameter=false or --/some/path/to/parameter=FaLsE produces the same result

  2. If you need to set the string value "true" or "false" escape it with double quotes: --/some/path/to/text_parameter=\"false\"

  3. It is also possible to use --/some/path/to/parameter=0 or --/some/path/to/parameter=1 to set a setting to true or false correspondingly. In this case the actual value in the settings will be an integer, but functions working with settings will correctly convert it to a boolean.

Setting a numeric or string value is straightforward:

> kit.exe --/some/number=7 --/another/number=1.5 --/some/string=test

If you need to set a string value that can be parsed as a number or a boolean - or if the string value contains whitespaces - use double quotes to escape it:

> kit.exe --/sets/string/value=\"7\" --/sets/string/with/whitespaces=\"string with spaces\"


Do not forget to escape the quotes so that the OS doesn’t remove them.

Changing an array value with command line

To set an array value you can:

  1. Specify individual array elements by adding their index in the array at the end of the path to the value:

for example, > kit.exe --/some/array/1=17 will change

"some": {
    "array" : [1, 2, 3],


"some": {
    "array" : [1, 17, 3],
  1. Specify all array elements in the form [value0,value1,...]:

for example, > kit.exe --/some/array=[8,11] replaces

"some": {
    "array" : [1, 2, 3],


"some": {
    "array" : [8, 11],


You can use whitespace in the square brackets ([val0,  val1, val2]), if you escape the whole expression with double quotes, in order to prevent the OS from separating it into several command line arguments: > kit.exe --/some/array="[ 8,  11]"

It is also possible to assign a proper JSON as a parameter value:

> kit.exe --/my/json/param={\"num\":1,\"str\":\"test\",\"arr\":[1,2,3],\"obj\":{\"info\":42}} results in

"my": {
    "json" : {
        "param" : {
            "num": 1,
            "str": "test",
            "arr": [
            "obj": {
                "info": 42

Passing Command Line arguments to extensions

Kit ignores all command line arguments after --. It also writes those into the /app/cmdLineUnprocessedArgs setting. Extensions can use this setting to access them and process as they wish.

Code Examples

Get Setting

# Settings/Get Setting
import carb.settings

settings = carb.settings.get_settings()

# get a string

# get an array (tuple)

# get an array element syntax:

# get a whole dictionary
exts = settings.get("/app/exts")

# get `None` if doesn't exist

Set Setting

# Settings/Set Setting
import carb.settings

settings = carb.settings.get_settings()

# set different types into different keys
# guideline: each extension puts settings in /ext/[ext name]/ and lists them extension.toml for discoverability
settings.set("/exts/", 23)
settings.set("/exts/", 502.45)
settings.set("/exts/", False)
settings.set("/exts/", "summer")
settings.set("/exts/", [9,13,17,21])
settings.set("/exts/", { "a": 2, "b": "winter"})

# print all:

Set Persistent Setting

# Settings/Set Persistent Setting
import carb.settings

settings = carb.settings.get_settings()

# all settings stored under "/persistent" saved between sessions
# run that snippet again after restarting an app to see that value is still there:
key = "/persistent/exts/"
print("{}: {}".format(key, settings.get(key)))
settings.set(key, "string from previous session")

# Below is a setting with location of a file where persistent settings are stored.
# To reset settings: delete it or run kit with `--reset-user`
print("persistent settings are stored in: {}".format(settings.get("/app/userConfigPath")))

Subscribe To Setting Changes

# Settings/Subscribe To Setting Changes
import carb.settings

settings = carb.settings.get_settings()

def on_change(value, change_type: carb.settings.ChangeEventType):
    print(value, change_type)

# subscribe to value changes, returned object is subscription holder. To unsubscribe - destroy it.
subscription1 ="/exts/", on_change)

settings.set("/exts/", 23)
settings.set("/exts/", "fall")
settings.set("/exts/", None)
settings.set("/exts/", 89)
subscription1 = None # no more notifications
settings.set("/exts/", 100)

Kit Kernel Settings

/app/enableStdoutOutput (default: true)

Enable kernel standard output. E.g. when extension starts etc.

/app/disableCmdArgs (default: false)

Disable processing of any command line arguments.

/app/printConfig (default: false)

Print all settings on startup.

/app/settings/persistent (default: true)

Enable saving persistent settings (user.config.json). It autosaves changed persistent settings (/persistent namespace) each frame.

/app/settings/loadUserConfig (default: true)

Enable loading persistent settings (user.config.json) on startup.

/app/hangDetector/enabled (default: false)

Enable hang detector.

/app/hangDetector/alwaysEnabled (default: false)

It true ignore /app/hangDetector/disableReasons settings and keep hang detector always enabled. Normally it is disabled during startup and extensions can choose to disable it.

/app/hangDetector/timeout (default: 120)

Hang detector timeout to trigger (in seconds).

/app/quitAfter (default: -1)

Automatically quit app after X frames (if X is positive).

/app/quitAfterMs (default: -1.0)

Automatically quit app after X milliseconds (if X is positive).

/app/fastShutdown (default: false)

Do not perform full extension shutdown flow. Instead only let subscribers handle IApp shutdown event and terminate.

/app/python/logSysStdOutput (default: true)

Intercept and log all python standard output in carb logger (info level).