Creating custom packages

The Unity Package Manager is the official package management system for Unity. It does the following:

• Allows Unity to distribute new features and update existing features quickly and easily.
• Provides a platform for users to discover and share reusable components.
• Promotes Unity as an extendable and open platform.

You can use the Package Manager to define project dependencies, resolve package dependencies, download packages, add packages, and integrate content in your projects.

For general information on what a package is and how the Unity Package Manager works, see the PackagesPackages are collections of assets to be shared and re-used in Unity. The Unity Package Manager (UPM) can display, add, and remove packages from your project. These packages are native to the Unity Package Manager and provide a fundamental method of delivering Unity functionality. However, the Unity Package Manager can also display Asset Store packages that you downloaded from the Asset Store. More info
See in Glossary documentation.

Overview

Packages can contain the following:

• C# scripts
• Assemblies
• Native plug-ins
• Models, Textures, animation and audio clipsA container for audio data in Unity. Unity supports mono, stereo and multichannel audio assets (up to eight channels). Unity can import .aif, .wav, .mp3, and .ogg audio file format, and .xm, .mod, .it, and .s3m tracker module formats. More info
  See in Glossary, and other assets.

Note: Package Manager doesn’t support streaming assets in packages. Use the Addressables package instead.

Each package also contains a Package manifestEach package has a manifest, which provides information about the package to the Package Manager. The manifest contains information such as the name of the package, its version, a description for users, dependencies on other packages (if any), and other details. More info
See in Glossary file that includes information such as the package name, its version, a list of its dependencies, and the URL to its repository.

Procedure

To create a new package:

1. Create an empty shell for the package using one of these methods:

   • Set up an embedded package.
   • Set up a local package.

2. Make sure the layout of your folder structure follows the package layout convention for Unity packages. For example, if you have Editor and Runtime libraries, make sure you store them under the Editor and Runtime folders.

3. If your package includes code, make sure the package layout you created has the necessary assembly definition files. For information about creating and defining assembly definition files, see Assembly definition and packages. For additional information, see Assembly definitions.

   Note: If the console windowA Unity Editor window that shows errors, warnings and other messages generated by Unity, or your own scripts. More info
   See in Glossary reports a warning after adding an assembly definition file, save your project, close it, then reopen it.

4. Add your tools, libraries, and any assets your package requires.

5. Add tests to your package. Tests are essential for ensuring that the package works as expected in different scenarios:

   • Write all your Editor Tests in Tests/Editor.
   • Write all your Play Mode Tests in Tests/Runtime.

6. If you have samples for your package, add them to the proper samples subfolder.

   Note: Packages can contain only samples, but you can also include samples as part of a tool or template package using the same layout and JSON structure.

7. You can update the CHANGELOG.md file every time you publish a new version. Every new feature or bug fix should have a trace in this file. For more details on the chosen changelog format, see the Keep a Changelog documentation.

   This step is optional for packages that you don’t share, but strongly recommended for shared packages, so that users know which version best suits their needs.

   Tip: You can provide a link to an external web page where you host this package’s changelog by setting the changelogUrl property in your package’s package.json manifest file.

8. You can include licenses and third-party notices in the LICENSE.md and THIRD PARTY NOTICES.md files.

   This step is optional for packages that you don’t share, but strongly recommended for shared packages, so that your users don’t misuse your packages or violate any third-party licenses.

   Tip: You can provide a link to an external web page where you host this package’s licensing and third-party notices by setting the licensesUrl property in your package’s package.json manifest file.

9. Document your package.

   Tip: You can provide a link to an external web page where you host this package’s documentation by setting the documentationUrl property in your package’s package.json manifest file.

10. Share your package.

Creating a new embedded package

Follow these instructions if you want to create a custom package inside your project folder.

Note: These instructions are part of the larger procedure for Creating custom packages.

1. Open the Unity Hub, and create an empty project on your computer.

   You can also use an existing project on your computer, and embed the package under your project or install the package from a local folder. However, starting with a new project makes the package contents less prone to errors.

2. Using your computer’s file manager (for example the Windows File Explorer or the macOS Finder), navigate to your project folder and locate the Packages subdirectory.

3. Create a new subdirectory for your package inside the Packages folder using a name that matches the package name and follows the naming conventions. For example, if your package name is com.example.mypackage, create a subdirectory called com.example.mypackage.

   Note: This is particularly important if your package contains assets, because the AssetDatabase looks for an asset path that matches Packages/<your-package-name>/Assets, regardless of the actual folder name.

4. Open your preferred text editor and create a JSON file called package.json in the root of the package folder.

5. Fill out all required and recommended fields in the package.json file. You can use the package manifest example as a reference.

When you reopen Unity, the new package appears in the Package Manager window and in the Project windowA window that shows the contents of your Assets folder (Project tab) More info
See in Glossary, where you can view and modify the package contents. If you select the package.json file in the Project window, you can also modify its JSON values directly in the InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
See in Glossary window.

Return to the main procedure to complete the creation of your package.

Creating a new local package

Follow these instructions if you want to create a custom package outside your project folder.

Note: These instructions are part of the larger procedure for Creating custom packages.

1. Using your computer’s file manager (for example the Windows File Explorer or the macOS Finder), create a folder for your package.

   You can also use an existing location if you’ve already created some content for your package.

2. Open your preferred text editor and create a JSON file called package.json in the root of the package folder.

3. Fill out all required and recommended fields in the package.json file, making sure the name property follows the naming conventions. You can use the package manifest example as a reference.

4. In Unity, create a new project or open an existing project.

5. Open the Package Manager window and follow the instructions for installing a local package, using the package.json file you just created. This step is essential for ensuring the creation of the required .meta file.

The new package appears in the Package Manager window and in the Project window, where you can view and modify the package contents. If you select the package.json file in the Project window, you can also modify its JSON values directly in the Inspector window.

Return to the main procedure to complete the creation of your package.