Class library for doing multi-part form POSTs, including posting files.
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Latest commit 08787b4 Apr 17, 2010 @jptoto Added README.markdown


MultiFormPoster is a .NET 3.5 class library for creating form POSTs

License: Apache License 2.0

Key Features

  • Multi-Part form posts
  • Basic HTTP Auth

Basic Usage

// If you're going to be uploading a file, you'll need to first read it in as a byte array
FileStream fs = new FileStream("c:\\test.jpg", FileMode.Open, FileAccess.Read);
byte[] data = new byte[fs.Length];
fs.Read(data, 0, data.Length);

// Generate post objects
Dictionary<string, object> postParameters = new Dictionary<string, object>();

// Adding a file as the post parameter Be sure to add the content-type as well
postParameters.Add("file", new FileParameter(data, "test.jpg", "image/jpeg"));

// Adding a normal name/value post parameter
postParameters.Add("name", "FileName");

// Create request and receive response
string postURL = "";

// Create an HttpWebResponse object and use either the MultipartFormDataPost WITH Basic HttpAuth params or without
HttpWebResponse webResponse = FormUpload.MultipartFormDataPost(postURL, "UserName", "Password", postParameters);

// Process response
StreamReader responseReader = new StreamReader(webResponse.GetResponseStream());
string fullResponse = responseReader.ReadToEnd();
// Do something with fullResponse. This may contain xml, json, or whatever the API you're posting to is using.


  • Add ActiveDirectry Auth
  • Add cookie container (some sites authorize you based on the cookie they already dropped)


This class is based heavily on a blog post by Brian Grinstead which you may find here:

I've taken his example and blown it out a bit to add some functionality such as basic http auth functions.