.NET client libraries for Azure DevOps Services (and TFS)


Client libraries are available for .NET developers who build Windows apps and services that integrate with Azure DevOps Services. Client libraries integrate with work item tracking, version control, build, and other services. These packages replace the traditional TFS Client OM installer and make it easy to acquire and redistribute the libraries needed by your app or service.

Dependency diagram...


  • Downloadable from nuget.org and easily importable into your Visual Studio projects
  • Libraries are licensed for redistribution in your apps and services (view the license)
  • Access both traditional client object model APIs and new REST APIs


REST-based clients only work with Azure DevOps Services and TFS 2015 (not previous versions of TFS) To learn more about extending and integrating with Azure DevOps Services and Team Foundation Server using the client libraries, see Extending Team Foundation

Package and TFS version mapping table

Package version TFS Version
17.x.x Azure DevOps Server vNext
16.153.x versions >= Azure DevOps Server 2019 Update 1
16.143.x versions >= Azure DevOps Server 2019
15.131.x versions >= TFS 2018 Update 1
15.112.x versions >= TFS 2017 Update 1
14.102.x versions >= TFS 2015 Update 3
14.95.x versions >= TFS 2015 Update 2
14.89.x versions >= TFS 2015 Update 1
14.83.x versions >= TFS 2015

REST packages

Packages Description Binaries
Microsoft.VisualStudio.Services.Client​ Provides access to shared platform services such as organization, profile, identity, security, and more via public REST APIs. Microsoft.VisualStudio.Services.WebApi.dll, Microsoft.VisualStudio.Services.Common.dll, Microsoft.TeamFoundation.Common.dll
Microsoft.TeamFoundationServer.Client Provides access to version control, work item tracking, build, and more via public REST APIs. Microsoft.TeamFoundation.Build2.WebApi.dll, Microsoft.TeamFoundation.Core.WebApi.dll, Microsoft.TeamFoundation.WorkItemTracking.Process.WebApi.dll, Microsoft.TeamFoundation.SourceControl.WebApi.dll, Microsoft.TeamFoundation.TestManagement.WebApi.dll, etc.
Microsoft.VisualStudio.Services.InteractiveClient Supports applications that require interactive sign-in by a user. Microsoft.VisualStudio.Services.Client.Interactive.dll
Microsoft.VisualStudio.Services.Release.Client​ Provides access to the Release Service via public REST APIs. Microsoft.VisualStudio.Services.ReleaseManagement.WebApi.dll
Microsoft.TeamFoundation.DistributedTask.Common.Contracts​ Provides the models used to access the Distributed Task Service via public REST APIs. Microsoft.TeamFoundation.DistributedTask.Common.Contracts.dll
Microsoft.TeamFoundation.DistributedTask.WebApi Provides access to the Distributed Task Service via public REST APIs. Microsoft.TeamFoundation.DistributedTask.WebApi.dll
Microsoft.VisualStudio.Services.ServiceHooks.WebApi Provides access to the Service Hooks Service via public REST APIs. Microsoft.VisualStudio.Services.ServiceHooks.WebApi.dll
Microsoft.VisualStudio.Services.Gallery.WebApi Provides access to the Gallery Service via public REST APIs. Microsoft.VisualStudio.Services.Gallery.WebApi.dll
Microsoft.VisualStudio.Services.Notifications.WebApi Provides access to the Notifications Service via public REST APIs. Microsoft.VisualStudio.Services.Notifications.WebApi.dll
Microsoft.VisualStudio.Services.ExtensionManagement.WebApi Provides access to the Extension Management Service via public REST APIs. Microsoft.VisualStudio.Services.ExtensionManagement.WebApi.dll
Microsoft.VisualStudio.Services.MemberEntitlementManagement.WebApi Provides access to the Member Entitlement Management Service via public REST APIs. Microsoft.VisualStudio.Services.MemberEntitlementManagement.WebApi.dll
Microsoft.VisualStudio.Services.ServiceEndpoints.WebApi Provides access to the Service Endpoints via public REST APIs. Microsoft.VisualStudio.Services.ServiceEndpoints.WebApi.dll
Microsoft.VisualStudio.Services.Search.Client Provides access to the Search Service via public REST APIs. Microsoft.VisualStudio.Services.Search.Shared.WebApi.dll, Microsoft.VisualStudio.Services.Search.WebApi.dll
Microsoft.TeamFoundation.PublishTestResults​ This task can be used to Publish test results and upload test attachments on Azure DevOps. The following results formats are supported with this package: 1. JUnit - publish tests from Junit projects, 2. NUnit- publish tests from Nunit projects, 3. VSTest- publish tests from Visual Studio projects, 4. Xunit- publish tests from Xunit projects Microsoft.TeamFoundation.TestClient.PublishTestResults.dll
Microsoft.VisualStudio.Services.Audit.WebApi Provides access to the Audit Service via public REST APIs. Microsoft.VisualStudio.Services.Audit.WebApi.dll


If you have an existing Windows app or service that uses the TFS Client Object Model, use Microsoft.TeamFoundationServer.ExtendedClient

Soap package

Package Description Binaries
Microsoft.TeamFoundationServer.ExtendedClient​ Work with and manage version control, work items, and build, and other resources from your client application. This package does not support Net Standard Client OM. This package should only be used in instances where our REST APIs don't offer the functionality you need (i.e. creating workspaces in TFVC) Microsoft.TeamFoundation.Build.Client.dll, Microsoft.TeamFoundation.DeleteTeamProject.dll, Microsoft.TeamFoundation.Diff.dll, Microsoft.TeamFoundation.Git.Client.dll, Microsoft.TeamFoundation.SharePointReporting.Integration.dll , etc.


From a NuGet package manager command prompt:

PM> Install-Package Microsoft.TeamFoundationServer.ExtendedClient

Pattern for use

In general, you first create an authenticated connection to Azure DevOps Services or TFS, then get an HttpClient for the service you want to work with, and finally call methods against that service. Example:

using Microsoft.VisualStudio.Services.Common;
using Microsoft.VisualStudio.Services.Client;
using Microsoft.TeamFoundation.SourceControl.WebApi;
using Microsoft.VisualStudio.Services.WebApi;

const String c_collectionUri = "https://dev.azure.com/fabrikam";
const String c_projectName = "MyGreatProject";
const String c_repoName = "MyRepo";

// Interactively ask the user for credentials, caching them so the user isn't constantly prompted
VssCredentials creds = new VssClientCredentials();
creds.Storage = new VssClientCredentialStorage();

// Connect to Azure DevOps Services
VssConnection connection = new VssConnection(new Uri(c_collectionUri), creds);

// Get a GitHttpClient to talk to the Git endpoints
GitHttpClient gitClient = connection.GetClient<GitHttpClient>();

// Get data about a specific repository
var repo = gitClient.GetRepositoryAsync(c_projectName, c_repoName).Result;


You can find detailed, up-to-date reference documentation in the Azure DevOps Services .NET SDK API Reference browser.


You can check out samples on our .NET Samples Page or directly on our .NET GitHub Repo.

Known issues

Interactive authentication dialog doesn't appear when using the Azure DevOps OM in a Single Threaded Apartment (STA)

There's a known issue that prevents the interactive authentication dialog from appearing in cases where your code is running from a Single Threaded Apartment (STA). This issue can commonly occur from WPF applications. To work around this issue, you can change your initialization method to be async and request authentication as in the following example:

async void InitAzureDevOps()
    Uri _uri = new Uri("https://dev.azure.com/MyAccount/");

    var creds = new VssClientCredentials(new WindowsCredential(false),
                                         new VssFederatedCredential(false),

    VssConnection vssConnection = new VssConnection(_uri, creds);
    await vssConnection.ConnectAsync();



Using NetStandard 2.0 versions of the Azure DevOps OM

As of the released version 16.143.1 of our NuGet packages, we support NetStandard 2.0. These packages correlate with Azure DevOps Server 2019 RTW and are fully compatible with the Azure DevOps service.

Microsoft.TeamFoundationServer.ExtendedClient package doesn't have NetStandard support

The Microsoft.TeamFoundationServer.ExtendedClient currently doesn't support a NetStandard compliant version. This package includes our older SOAP object model, which has been replaced by our newer REST object model. At this point, we're no longer investing in the older SOAP object model, and have no plans to create a NetStandard version of it.