Experimental packages
Experimental packages are new packages or experimental modifications made to mature packages. Unity does not support Experimental packages because they are in the early stages of development.
| Note: |
|---|
| Prior to Unity Editor version 2021.1, the Package Manager used the “Preview” state to describe packages that are experimental or risky but otherwise mature, as well as packages that have not yet been fully validated as safe to use in production. Starting with 2021.1, the “Preview” state no longer exists, and packages can either be “Experimental” or “Pre-release”. This provides a clearer distinction between packages that are mature but risky to use, and packages that are almost fully mature. |
Experimental packages can go through many changes before they are ready to be released in a specific version of Unity. At some point in the future, they might pass the verification requirements; however, they might also be deprecated instead. Because there is no guarantee for future support, you should not use experimental packages in production.
Packages in this state do not usually appear in the Unity Registry context of the Unity Editor, even though they are on Unity’s official package registry server. These packages are not discoverable in the Package Manager window because:
- They are too risky to use in production. Some of these packages require a lot of training and expertise and are therefore recommended only in specific circumstances.
- They provide shared or additional functionality to existing packages. You shouldn’t use them on their own because they are “support” packages only.
Undiscoverable packages can still appear in the Package Manager window if they were previously installed in your project or installed as dependencies of supported packages. However, they are hidden so that you don’t discover them by accident and use them without realizing the risks. If they do appear in the Editor, they are always marked in the Package Manager window with the 
label (details view) and the 
label (list view). Also, the following menu appears as a warning in the Editor:
For a list of stable packages verified for this release, see Released packages.
For more information about package states, see Package states and lifecycle.