c# - How to make an HTTP POST web request

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+, .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(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+, .NET Core 2.0+

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"); }