How to make an HTTP POST web request

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

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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.

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

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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;

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

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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

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

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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;

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