Working with APIs and HttpClient

C# in Visual Studio 2026 — a hands-on guide for developers at every level.

HttpClient

HttpClient is the standard way to make HTTP requests in .NET. Always reuse a single instance (or use IHttpClientFactory in real apps) to avoid socket exhaustion.

GET Request

using System.Net.Http;
using System.Net.Http.Json;

using var client = new HttpClient();
client.BaseAddress = new Uri("https://jsonplaceholder.typicode.com/");

var post = await client.GetFromJsonAsync<Post>("posts/1");
Console.WriteLine(post?.Title);

POST Request

record NewPost(string Title, string Body, int UserId);

var newPost = new NewPost("Test", "Hello API", 1);
HttpResponseMessage response = await client
    .PostAsJsonAsync("posts", newPost);

response.EnsureSuccessStatusCode();
var created = await response.Content.ReadFromJsonAsync<Post>();
Console.WriteLine($"Created with ID: {created?.Id}");

Error Handling

try
{
    var result = await client.GetFromJsonAsync<Post>("posts/9999");
}
catch (HttpRequestException ex) when (ex.StatusCode == HttpStatusCode.NotFound)
{
    Console.WriteLine("Post not found (404)");
}