.NET client libraries

Azure DevOps Services | Azure DevOps Server 2022 - Azure DevOps Server 2019

Client libraries are available for .NET developers who build Windows apps and services that integrate with Azure DevOps. 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.


Find the corresponding .NET client class and API method, using .NET Client Library Samples and Azure DevOps API Reference.

Dependency diagram

Dependency diagram shows the relationship between Services.Client, Services.InteractiveClient, and TeamFoundationServer.Client.


  • 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 REST APIs


REST-based clients only work with Azure DevOps and TFS 2015 or later. For more information about extending and integrating with Azure DevOps using the client libraries, see Extending Team Foundation.

Package and Azure DevOps version-mapping table

Package version Azure DevOps version
16.205.x versions >= Azure DevOps Server 2022
16.170.x versions >= Azure DevOps Server 2020
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

For the latest preview versions, see the NuGet packages gallery.

REST packages

Packages and description Binaries
Provides access to shared platform services via public REST APIs, like organization, profile, identity, security, and more.
Microsoft.VisualStudio.Services.WebApi.dll, Microsoft.VisualStudio.Services.Common.dll, Microsoft.TeamFoundation.Common.dll
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, and so on.
Supports applications that require interactive sign-in by a user.
Provides access to the Release Service via public REST APIs.
Provides the models used to access the Distributed Task Service via public REST APIs.
Provides access to the Distributed Task Service via public REST APIs.
Provides access to the Service Hooks Service via public REST APIs.
Provides access to the Gallery Service via public REST APIs.
Provides access to the Notifications Service via public REST APIs.
Provides access to the Extension Management Service via public REST APIs.
Provides access to the Member Entitlement Management Service via public REST APIs.
Provides access to the Service Endpoints via public REST APIs.
Provides access to the Search Service via public REST APIs.
Microsoft.VisualStudio.Services.Search.Shared.WebApi.dll, Microsoft.VisualStudio.Services.Search.WebApi.dll
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
Provides access to the Audit Service via public REST APIs.
Provides access to the pipeline approvals, checks, and authorization via public REST APIs.


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

Soap package

Package and description Binaries
Work with and manage version control, work items, and build, and other resources from your client application. This package doesn't support Net Standard Client OM. Only use this package when our REST APIs don't offer the functionality you need (for example, 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, and so on.


Install from a NuGet package manager command prompt:

PM> Install-Package Microsoft.TeamFoundationServer.ExtendedClient


To create an authenticated connection to Azure DevOps, get an HttpClient for the service you want to work with, and then call methods against that service.

See the following examples:

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";

Uri orgUrl = new Uri(c_collectionUri);

// Connect to Azure DevOps Services
VssConnection connection = new VssConnection(orgUrl, new VssBasicCredential(string.Empty, personalAccessToken));

// Get a GitHttpClient to talk to the Git endpoints
using (GitHttpClient gitClient = connection.GetClient<GitHttpClient>())
    // Get data about a specific repository
    var repo = gitClient.GetRepositoryAsync(c_projectName, c_repoName).Result;

Authentication paths that produce an interactive dialog aren't available in the .NET Standard version of the .NET client libraries. When you're using the .NET Standard version, provide your credentials more explicitly to authenticate, like in the following example.

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

namespace ConsoleApp1
    class Program
        const string collectionUri = "https://dev.azure.com/fabrikam";
        const string projectName = "MyGreatProject";
        const string repoName = "MyRepo";
        const string pat = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";

        static void Main(string[] args)
            var creds = new VssBasicCredential(string.Empty, pat);
            // Connect to Azure DevOps Services
            var connection = new VssConnection(new Uri(collectionUri), creds);
            // Get a GitHttpClient to talk to the Git endpoints
            using var gitClient = connection.GetClient<GitHttpClient>();
            // Get data about a specific repository
            var repo = gitClient.GetRepositoryAsync(projectName, repoName).Result;

For more authentication samples, see .NET Samples.


For more information and for up-to-date reference documentation, see the .NET API browser.


Check out samples on our .NET Samples Page or directly on our .NET GitHub Repo.

For more information on NuGet packages, see Microsoft.VisualStudio.Services.Client.

Known issues

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

The interactive authentication dialog doesn't appear 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

For 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 Azure DevOps.

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

The Microsoft.TeamFoundationServer.ExtendedClient doesn't support a NetStandard compliant version.


This package includes our older SOAP object model, which we replaced by our newer REST object model. We're no longer investing in the older SOAP object model, and have no plans to create a NetStandard version of it.