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Work with VSIX projects

VSIX projects are the standard way to package Visual Studio extensions for distribution. Whether you're building a VisualStudio.Extensibility extension or a VSSDK-based extension, the output is a .vsix file that users install through the Extension Manager or the Visual Studio Marketplace.

Important

This article covers older VSIX project templates and maintaining existing packaging projects. For new projects in Visual Studio 18.11 or later, use the Modern VSIX Project Template, which handles VSIX packaging. These are alternative project workflows, not consecutive steps. Choose based on your development environment and existing project, not just the Visual Studio version your extension targets.

Create a VSIX project

VSIX project templates are available in the Create a new project dialog. Search for "VSIX" to find them:

  • VisualStudio.Extensibility Extension — For out-of-process extensions using the new extensibility model.
  • VSIX Project — For VSSDK-based extensions or wrapping multiple extension outputs.
  • VisualStudio.Extensibility Extension with VSSDK Compatibility — For hybrid extensions using both models.
  • Empty VSIX Project — A blank VSIX container for packaging existing components.

Tip

For new extensions, we recommend Visual Studio 18.11 or later and the Modern VSIX Project template. Select VisualStudio.Extensibility (Out-Of-Process) for features supported by that model; select a VSSDK or hybrid option only when you need in-process APIs. On earlier Visual Studio versions, use the VisualStudio.Extensibility Extension template, or the VSSDK-compatible template when you need VSSDK APIs.

Package extensions in a VSIX project

Note

The source.extension.vsixmanifest file and the steps below apply to VSSDK and hybrid extensions only. VisualStudio.Extensibility (out-of-process) extensions generate their metadata from ExtensionConfiguration.Metadata in code — no manifest file is needed.

You can package an existing extension or component by wrapping it in a VSIX project:

  1. Create a VSIX project using any of the templates above.
  2. The source.extension.vsixmanifest file opens in the Manifest Designer.
  3. On the Assets tab, select New to add components.
  4. In the Type list, choose the type of asset to add (for example, Microsoft.VisualStudio.MefComponent, Microsoft.VisualStudio.VsPackage).
  5. Set the Source to A project in current solution and select the project.

The VSIX format supports packaging VSPackages, MEF components, assemblies, project templates, item templates, toolbox controls, and custom extension types.

Add dependencies to a VSIX package

You can configure your VSIX to require other extensions as dependencies. When a user installs your extension, the installer verifies that all required dependencies are present.

To add a dependency:

  1. Open source.extension.vsixmanifest in the Design view.
  2. Go to the Dependencies tab and select New.
  3. Choose Installed extension to select a dependency from already-installed extensions, or File on file system to reference another VSIX directly.

Require a specific Visual Studio version

To target a minimum Visual Studio build number, set the InstallationTarget version range:

<Installation>
  <InstallationTarget Id="Microsoft.VisualStudio.Community" Version="[17.0,)" />
</Installation>

Note

Starting with Visual Studio 2026, only the lower bound of the version range is evaluated. The upper bound is ignored for compatibility purposes. See Extension compatibility.

Create an extension pack

An extension pack is a set of extensions that can be installed together. Extension packs let you share your favorite extensions with colleagues or bundle a set of extensions for a scenario.

To create an extension pack:

  1. Create a new VSIX Project.
  2. Right-click the project in Solution Explorer and select Add > New Item.
  3. Select the Extension Pack template. This adds a .vsext file.
  4. Edit the .vsext file to list the extensions to include:
{
  "id": "MyExtensionPack",
  "name": "My Extension Pack",
  "description": "A curated set of extensions for my team",
  "version": "1.0.0.0",
  "extensions": [
    {
      "vsixId": "41858b2d-ff0b-4a43-80b0-f1b2d6084935",
      "name": "AlignAssignments"
    },
    {
      "vsixId": "42374550-426a-400e-96f9-237682e8dea6",
      "name": "CopyAsHtml"
    }
  ]
}
  1. Find the vsixId on the Visual Studio Marketplace ↗ — open the extension page and select Copy ID.
  2. Build and publish the project. See Publish to the Marketplace.

Note

Extension packs can only install extensions available on the Visual Studio Marketplace ↗ or a private gallery.

Extension architecture overview

Understanding how Visual Studio loads your extension helps you make better packaging and deployment decisions.

VisualStudio.Extensibility (out-of-process)

Out-of-process extensions run in a separate process from Visual Studio, communicating over a JSON-RPC channel:

┌─────────────────────┐       JSON-RPC        ┌──────────────────────┐
│   Visual Studio     │◄─────────────────────►│  Extension Process   │
│   (DevEnv.exe)      │                        │  (.NET 8+)           │
│                     │                        │                      │
│  ┌───────────────┐  │                        │  ┌────────────────┐  │
│  │ Extension Host│  │                        │  │ Your Extension │  │
│  │ (manages      │  │                        │  │ Code           │  │
│  │  lifecycle)   │  │                        │  └────────────────┘  │
│  └───────────────┘  │                        └──────────────────────┘
└─────────────────────┘

Key characteristics:

  • Extension runs on modern .NET (8+)
  • Extension process crashes are less likely to bring down Visual Studio
  • Install/uninstall without restarting VS
  • Per-user installation (no admin required)

VSSDK / Hybrid (in-process)

In-process extensions are loaded directly into the Visual Studio process:

┌──────────────────────────────────────────┐
│   Visual Studio (DevEnv.exe)             │
│                                          │
│  ┌────────────────┐  ┌────────────────┐  │
│  │ VS Core        │  │ Your Extension │  │
│  │ Services       │◄─┤ (.NET Framework│  │
│  │                │  │  or hybrid)    │  │
│  └────────────────┘  └────────────────┘  │
└──────────────────────────────────────────┘

Key characteristics:

  • Full access to all VS APIs and services
  • Limited to .NET Framework (unless hybrid)
  • Extension bugs can affect VS stability
  • Requires VS restart on install/update

What's in a .vsix package

A .vsix file is a ZIP archive with a standard structure. The contents differ by extension model:

Component VisualStudio.Extensibility VSSDK
Extension metadata ExtensionConfiguration in code source.extension.vsixmanifest
Extension binaries Your .NET 8+ DLLs Your .NET Framework DLLs
Localization files .vsextension/string-resources.json .vsixlangpack files
Content types [Content_Types].xml [Content_Types].xml
Package manifest Auto-generated extension.vsixmanifest Hand-authored source.extension.vsixmanifest

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