C# HTTP Examples

C# Basic

C# Data Type

C# OOP

C# IO

C# Graphics & UI

C# Advanced

HTTP POST request in C#

To send an HTTP POST web request to a URL in C#, you can use the HttpClient class along with the PostAsync method. Here is an example:

using System.Net.Http;
using System.Threading.Tasks;

// ...

public async Task<string> PostRequest(string url, string data)
{
    using (var client = new HttpClient())
    {
        var content = new StringContent(data, Encoding.UTF8, "application/json");
        var response = await client.PostAsync(url, content);
        return await response.Content.ReadAsStringAsync();
    }
}

In this example, we use the StringContent class to create the HTTP request body with the data parameter. We also set the content type to application/json using the MediaTypeHeaderValue class. Finally, we call the PostAsync method of the HttpClient instance with the URL and content.

To send an asynchronous HTTP POST web request to a URL in C#, you can use the PostAsync method with the await keyword to make the call asynchronously. Here is an example:

using System.Net.Http;
using System.Threading.Tasks;

// ...

public async Task<string> PostRequestAsync(string url, string data)
{
    using (var client = new HttpClient())
    {
        var content = new StringContent(data, Encoding.UTF8, "application/json");
        var response = await client.PostAsync(url, content);
        return await response.Content.ReadAsStringAsync();
    }
}

In this example, we use the async and await keywords to make the PostAsync method call asynchronous. The rest of the code is similar to the previous example.

C# HttpClient POST example:

Basic example of making an HTTP POST request using HttpClient.

Code snippet:

using (HttpClient client = new HttpClient())
{
    var content = new StringContent("Hello, World!", Encoding.UTF8, "text/plain");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
    // Process response
}

C# HTTPClient send POST request:

Sending an HTTP POST request using HttpClient.

Code snippet:

HttpClient client = new HttpClient();
var content = new StringContent("Hello, World!", Encoding.UTF8, "text/plain");
HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);

POST request in C# using WebClient:

Making an HTTP POST request using WebClient.

Code snippet:

using (WebClient client = new WebClient())
{
    var data = new NameValueCollection
    {
        { "key1", "value1" },
        { "key2", "value2" }
    };
    byte[] result = client.UploadValues("https://api.example.com/post", "POST", data);
    // Process result
}

Asynchronous HTTP POST request in C#:

Performing an asynchronous HTTP POST request.

Code snippet:

using (HttpClient client = new HttpClient())
{
    var content = new StringContent("Hello, World!", Encoding.UTF8, "text/plain");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
    // Process response
}

Sending JSON in POST request C#:

Including JSON data in an HTTP POST request.

Code snippet:

using (HttpClient client = new HttpClient())
{
    var data = new { key1 = "value1", key2 = "value2" };
    var json = JsonConvert.SerializeObject(data);
    var content = new StringContent(json, Encoding.UTF8, "application/json");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
    // Process response
}

C# HTTPClient POST request with form data:

Sending form data in an HTTP POST request using HttpClient.

Code snippet:

using (HttpClient client = new HttpClient())
{
    var formData = new MultipartFormDataContent
    {
        { new StringContent("value1"), "key1" },
        { new StringContent("value2"), "key2" }
    };
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", formData);
    // Process response
}

REST API POST request in C#:

Making a POST request to a REST API endpoint.

Code snippet:

using (HttpClient client = new HttpClient())
{
    var data = new { key1 = "value1", key2 = "value2" };
    var json = JsonConvert.SerializeObject(data);
    var content = new StringContent(json, Encoding.UTF8, "application/json");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/api/resource", content);
    // Process response
}

Deserialize JSON from POST request in C#:

Deserializing JSON content from an HTTP POST response.

Code snippet:

using (HttpClient client = new HttpClient())
{
    var data = new { key1 = "value1", key2 = "value2" };
    var json = JsonConvert.SerializeObject(data);
    var content = new StringContent(json, Encoding.UTF8, "application/json");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
    if (response.IsSuccessStatusCode)
    {
        string jsonResponse = await response.Content.ReadAsStringAsync();
        var result = JsonConvert.DeserializeObject<MyModel>(jsonResponse);
        // Process result
    }
}

HTTP POST request with headers in C#:

Including headers in an HTTP POST request.

Code snippet:

using (HttpClient client = new HttpClient())
{
    client.DefaultRequestHeaders.Add("Authorization", "Bearer your_access_token");
    var content = new StringContent("Hello, World!", Encoding.UTF8, "text/plain");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
    // Process response
}

C# HTTP POST request timeout:

Setting a timeout for an HTTP POST request in C#.

Code snippet:

using (HttpClient client = new HttpClient())
{
    client.Timeout = TimeSpan.FromSeconds(10); // Set timeout to 10 seconds
    var content = new StringContent("Hello, World!", Encoding.UTF8, "text/plain");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
    // Process response
}

Handling redirects in C# HTTP POST request:

Following redirects in an HTTP POST request.

Code snippet:

using (HttpClientHandler handler = new HttpClientHandler())
using (HttpClient client = new HttpClient(handler))
{
    handler.AllowAutoRedirect = true;
    var content = new StringContent("Hello, World!", Encoding.UTF8, "text/plain");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
    // Process response
}

C# HTTP POST request with authentication:

Making an authenticated HTTP POST request.

Code snippet:

using (HttpClient client = new HttpClient())
{
    var credentials = new NetworkCredential("username", "password");
    client.DefaultRequestHeaders.Authorization = new CredentialCache { { new Uri("https://api.example.com"), "Basic", credentials } };
    var content = new StringContent("Hello, World!", Encoding.UTF8, "text/plain");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
    // Process response
}

URL encoding in C# HTTP POST request:

Encoding parameters in the URL for an HTTP POST request.

Code snippet:

string parameterValue = "value with spaces";
string encodedValue = Uri.EscapeDataString(parameterValue);
var content = new StringContent($"key={encodedValue}", Encoding.UTF8, "application/x-www-form-urlencoded");

C# POST request with query string:

Including query parameters in an HTTP POST request.

Code snippet:

using (HttpClient client = new HttpClient())
{
    var parameters = new Dictionary<string, string>
    {
        { "param1", "value1" },
        { "param2", "value2" }
    };
    var content = new FormUrlEncodedContent(parameters);
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
    // Process response
}

C# HTTP POST request error handling:

Handling errors in an HTTP POST request.

Code snippet:

using (HttpClient client = new HttpClient())
{
    var content = new StringContent("Hello, World!", Encoding.UTF8, "text/plain");
    try
    {
        HttpResponseMessage response = await client.PostAsync("https://api.example.com/post", content);
        response.EnsureSuccessStatusCode(); // Throws exception for non-success status codes
        // Process response
    }
    catch (HttpRequestException ex)
    {
        // Handle exception
    }
}

Send file in HTTP POST request C#:

Including a file in an HTTP POST request.

Code snippet:

using (HttpClient client = new HttpClient())
using (var fileStream = File.OpenRead("path/to/file.txt"))
{
    var content = new MultipartFormDataContent();
    content.Add(new StreamContent(fileStream), "file", "file.txt");
    HttpResponseMessage response = await client.PostAsync("https://api.example.com/upload", content);
    // Process response
}