Send HTTP POST request in .NET

Question

How can I make an HTTP POST request and send data in the body?

Answer 1

There are several ways to perform HTTP GET and POST requests:

---

Method A: HttpClient (Preferred)

Available in: .NET Framework 4.5+, .NET Standard 1.1+, and .NET Core 1.0+.

It is currently the preferred approach, and is asynchronous and high performance. Use the built-in version in most cases, but for very old platforms there is a NuGet package.

using System.Net.Http;

Setup

It is recommended to instantiate one HttpClient for your application's lifetime and share it unless you have a specific reason not to.

private static readonly HttpClient client = new HttpClient();

See HttpClientFactory for a dependency injection solution.

---

• POST

    var values = new Dictionary<string, string>
    {
        { "thing1", "hello" },
        { "thing2", "world" }
    };
  
    var content = new FormUrlEncodedContent(values);
  
    var response = await client.PostAsync("http://www.example.com/recepticle.aspx", content);
  
    var responseString = await response.Content.ReadAsStringAsync();
  

• GET

    var responseString = await client.GetStringAsync("http://www.example.com/recepticle.aspx");
  

---

Method B: Third-Party Libraries

RestSharp

• POST

     var client = new RestClient("http://example.com");
     // client.Authenticator = new HttpBasicAuthenticator(username, password);
     var request = new RestRequest("resource/{id}");
     request.AddParameter("thing1", "Hello");
     request.AddParameter("thing2", "world");
     request.AddHeader("header", "value");
     request.AddFile("file", path);
     var response = client.Post(request);
     var content = response.Content; // Raw content as string
     var response2 = client.Post<Person>(request);
     var name = response2.Data.Name;
  

Flurl.Http

It is a newer library sporting a fluent API, testing helpers, uses HttpClient under the hood, and is portable. It is available via NuGet.

    using Flurl.Http;

---

• POST

    var responseString = await "http://www.example.com/recepticle.aspx"
        .PostUrlEncodedAsync(new { thing1 = "hello", thing2 = "world" })
        .ReceiveString();
  

• GET

    var responseString = await "http://www.example.com/recepticle.aspx"
        .GetStringAsync();
  

---

Method C: HttpWebRequest (not recommended for new work)

Available in: .NET Framework 1.1+, .NET Standard 2.0+, .NET Core 1.0+. In .NET Core, it is mostly for compatibility -- it wraps HttpClient, is less performant, and won't get new features.

using System.Net;
using System.Text;  // For class Encoding
using System.IO;    // For StreamReader

---

• POST

    var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/recepticle.aspx");
  
    var postData = "thing1=" + Uri.EscapeDataString("hello");
        postData += "&thing2=" + Uri.EscapeDataString("world");
    var data = Encoding.ASCII.GetBytes(postData);
  
    request.Method = "POST";
    request.ContentType = "application/x-www-form-urlencoded";
    request.ContentLength = data.Length;
  
    using (var stream = request.GetRequestStream())
    {
        stream.Write(data, 0, data.Length);
    }
  
    var response = (HttpWebResponse)request.GetResponse();
  
    var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
  

• GET

    var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/recepticle.aspx");
  
    var response = (HttpWebResponse)request.GetResponse();
  
    var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
  

---

Method D: WebClient (Not recommended for new work)

This is a wrapper around HttpWebRequest. Compare with HttpClient.

Available in: .NET Framework 1.1+, NET Standard 2.0+, and .NET Core 2.0+.

In some circumstances (.NET Framework 4.5-4.8), if you need to do a HTTP request synchronously, WebClient can still be used.

using System.Net;
using System.Collections.Specialized;

---

• POST

    using (var client = new WebClient())
    {
        var values = new NameValueCollection();
        values["thing1"] = "hello";
        values["thing2"] = "world";
  
        var response = client.UploadValues("http://www.example.com/recepticle.aspx", values);
  
        var responseString = Encoding.Default.GetString(response);
    }
  

• GET

    using (var client = new WebClient())
    {
        var responseString = client.DownloadString("http://www.example.com/recepticle.aspx");
    }