Why does curl work but C# fail?

Usually a header curl adds by default is missing in C#, or vice versa. Paste the curl above to see a normalized breakdown.

Is my request sent to Toolpaper?

No. Parsing and diffing run in your browser.

401 Unauthorized in C#

The server accepted the request shape but rejected your credentials or scheme. Paste your curl command to see what C# (HttpClient) would send and compare against the working request.

Quick answer

To convert a cURL command to C#, paste it into the Toolpaper workbench below. It parses the command in your browser and emits idiomatic C# code — headers, query string, request body, authentication (Bearer, Basic, API key), and cookies are all wired up automatically. No data is uploaded; conversion is fully client-side.

Prefer a different target? See the full cURL to C# reference, or jump to the same guide in JavaScript, Node.js, or Python.

InputcURL command

1 secret

MethodGET·Headers1·Body—· Chars 73

Output.NET · HttpClient(.NET)

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

class Program {
  static async Task Main() {
    using var handler = new HttpClientHandler { AllowAutoRedirect = false };
    using var client = new HttpClient(handler);
    using var request = new HttpRequestMessage(new HttpMethod("GET"), "https://api.example.com/me");
    request.Headers.TryAddWithoutValidation("Authorization", "Bearer YOUR_TOKEN");
    using var response = await client.SendAsync(request);
    var text = await response.Content.ReadAsStringAsync();
    Console.WriteLine(text);
  }
}

Inspect

Example

A representative curl command for this scenario. Paste your own above to convert an exact match.

curl input

curl https://api.example.com/me \
  -H "Authorization: Bearer YOUR_TOKEN"

Implementation notes

Double-check the Authorization header, ensure the token hasn't expired, and confirm the scheme (Bearer vs Basic vs API key) matches what the docs specify.
Use the Explain panel to enumerate exactly which headers, cookies, and TLS flags the curl request carries.
The In-browser Runner is a fast way to confirm whether the failure reproduces from the browser or only from the server.

Common mistakes

Comparing curl and C# without capturing both actual wire requests — mitmproxy or Charles pays off here.
Assuming a working curl means the API is happy — client differences (redirect handling, keep-alive, HTTP/2) surface as edge cases.
Silencing warnings instead of fixing them — every C# client has a way to log the outgoing request; turn it on.

Common questions

Why does curl work but C# fail?: Usually a header curl adds by default is missing in C#, or vice versa. Paste the curl above to see a normalized breakdown.
Is my request sent to Toolpaper?: No. Parsing and diffing run in your browser.

More guides in C#

C# hub →

CORS error when replaying curl in the browser · C#

/how-to/curl-cors-in-csharp

SSL certificate error · C#

/how-to/curl-ssl-in-csharp

The same guide in other languages

All guides →

In JavaScript

/how-to/curl-401-in-javascript

In Node.js

/how-to/curl-401-in-node

In Python

/how-to/curl-401-in-python

In Go

/how-to/curl-401-in-go

In Java

/how-to/curl-401-in-java

Full C# reference on the cURL to C# hub, or open the main converter for all 18 targets.