How to make an HTTP POST web request

Question

Canonical    How can I make an HTTP request and send some data using the POST method    I can do a GET request  but I have no idea of how to make a POST request

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Why is this not totally trivial  Doing the request is not and especially not dealing with the results and seems like there are some  NET bugs involved as well - see Bug in HttpClient GetAsync should throw WebException  not TaskCanceledException  I ended up with this code   static async Task lt  bool Success  WebExceptionStatus WebExceptionStatus  HttpStatusCode  HttpStatusCode  string ResponseAsString  gt  HttpRequestAsync HttpClient httpClient  string url  string postBuffer   null  CancellationTokenSource cts   null        try           HttpResponseMessage resp   null           if  postBuffer is null                resp   cts is null   await httpClient GetAsync url    await httpClient GetAsync url  cts Token              else               using  var httpContent   new StringContent postBuffer                     resp   cts is null   await httpClient PostAsync url  httpContent    await httpClient PostAsync url  httpContent  cts Token                                    var respString   await resp Content ReadAsStringAsync            return  resp IsSuccessStatusCode  WebExceptionStatus Success  resp StatusCode  respString          catch  WebException ex            WebExceptionStatus status   ex Status          if  status    WebExceptionStatus ProtocolError                   Get HttpWebResponse so that you can check the HTTP status code              using  HttpWebResponse httpResponse    HttpWebResponse ex Response                    return  false  status  httpResponse StatusCode  httpResponse StatusDescription                           else               return  false  status  null  ex ToString                       catch  TaskCanceledException ex            if  cts is object  amp  amp  ex CancellationToken    cts Token                   a real cancellation  triggered by the caller             return  false  WebExceptionStatus RequestCanceled  null  ex ToString               else                  a web request timeout  possibly other things                return  false  WebExceptionStatus Timeout  null  ex ToString                      catch  Exception ex            return  false  WebExceptionStatus UnknownError  null  ex ToString               This will do a GET or POST depends if postBuffer is null or not  if Success is true the response will then be in ResponseAsString  if Success is false you can check WebExceptionStatus  HttpStatusCode and ResponseAsString to try to see what went wrong

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Here s what i use in  NET 4 8 to make a HTTP POST request  With this code one can send multiple POST requests at a time Asynchronously  At the end of each request an event is raised  And also at the end of all request another event is raised  The one bellow is the core class  Imports System ComponentModel Imports System Text RegularExpressions Imports System Timers Imports System Windows Forms Imports AeonLabs Imports AeonLabs Environment Imports Newtonsoft Json  Public Class HttpDataCore     Public Property url As String     Public Property state As New environmentVarsCore     Public Property errorMessage As String    quot  quot      Public Property statusMessage As String     Public Property threadCount As Integer   25     Public Property numberOfRetryAttempts   5     Public Property queue As List Of  queue data struct      Public Property queueBWorker As Integer     has the size of threadCount     Public Property queueLock As New Object     Public Property retryAttempts As New  retry attempts     Public Property dataStatistics As List Of  data statistics      Public Property loadingCounter As Integer     Public Property CompletionPercentage As Integer   value range 0-100     Public Property IsBusy As Boolean      Public Structure  queue data struct         Dim vars As Dictionary Of String  String          Dim filenameOrSavePath As String                    full address file name or full adress folder path         Dim misc As Dictionary Of String  String          Dim status As Integer                               -1 - completed  0- not sent yet  1-already sent   processing      End Structure     Public Structure  retry attempts         Dim counter As Integer         Dim pattern As Integer         Dim previousPattern As Integer         Dim errorMessage As String     End Structure     Public Structure  data statistics         Dim filesize As Double         Dim bytesSentReceived As Double         Dim speed As Double     End Structure      Public WithEvents RestartQueueTimer As New Timers Timer     Public bwDataRequest   As BackgroundWorker      Public Event requestCompleted sender As Object  requestData As String   TODO add misc vars      Private sendToQueue As Boolean     Public Sub New ByVal Optional  state As environmentVarsCore   Nothing  ByVal Optional  url As String    quot  quot           queue   New List Of  queue data struct          dataStatistics   New List Of  data statistics          loadingCounter   0         sendToQueue   False         If  state IsNot Nothing AndAlso  url Equals  quot  quot   Then             url    state ServerBaseAddr  amp   state ApiServerAddrPath         ElseIf Not  url Equals  quot  quot   Then             url    url         Else             Throw New System Exception  quot Initialization err  state and url cannot be both null at same time quot           End If          If  state IsNot Nothing Then             state    state         End If      End Sub     Public Sub loadQueue ByVal vars As Dictionary Of String  String   ByVal Optional misc As Dictionary Of String  String    Nothing  ByVal Optional filenameOrSavePath As String   Nothing          Dim queueItem As New  queue data struct         queueItem vars   New Dictionary Of String  String          queueItem misc   New Dictionary Of String  String           queueItem vars   vars         queueItem status   0         queueItem misc   misc         queueItem filenameOrSavePath   filenameOrSavePath         queue Add queueItem      End Sub      Public Sub clearQueue           loadingCounter   0         queue   New List Of  queue data struct      End Sub     Public Sub startRequest           If bwDataRequest 0  Is Nothing Then             Throw New Exception  quot You need to call initialze first quot               Exit Sub         End If           startSendQueue           IsBusy   True          AddHandler RestartQueueTimer Elapsed  New ElapsedEventHandler AddressOf QueueTimerTick          With RestartQueueTimer              Enabled   True              Interval   500              Start           End With     End Sub      Private Sub QueueTimerTick ByVal sender As Object  ByVal e As ElapsedEventArgs          If QueuesToComplete queue  Equals 0  And QueuesToSend queue  Equals 0  Then             RestartQueueTimer Stop               queue   New List Of  queue data struct              RaiseEvent requestCompleted Me  Nothing              IsBusy   False             Exit Sub         End If          If retryAttempts counter  gt   numberOfRetryAttempts Then  ToDo a retry number of attempts before quits             Threading Thread CurrentThread CurrentUICulture   Globalization CultureInfo GetCultureInfo state currentLang              Dim MsgBox As messageBoxForm             MsgBox   New messageBoxForm retryAttempts errorMessage  amp   quot    quot   amp  My Resources strings tryAgain  amp   quot    quot   My Resources strings question  MessageBoxButtons YesNo  MessageBoxIcon Question              If MsgBox ShowDialog     DialogResult Yes Then                 Dim retry As  retry attempts                 With retry                      counter   0                      previousPattern   -1                      pattern   0                      errorMessage    quot  quot                  End With                 retryAttempts   retry                 startSendQueue               Else                 RestartQueueTimer Stop                   queue   New List Of  queue data struct                  RaiseEvent requestCompleted Me  Nothing                  IsBusy   False                 Exit Sub             End If             Exit Sub         ElseIf Not sendToQueue And QueuesToSend queue   gt  0 Then             startSendQueue           End If     End Sub      Private Sub startSendQueue           sendToQueue   True         While QueuesToSend queue   gt  0             For shtIndex   0 To threadCount                 For i   0 To queue Count - 1                     If Not bwDataRequest shtIndex  IsBusy Then                         SyncLock queueLock                             If queue ElementAt i  status Equals 0  Then                                 Dim data As New  queue data struct                                 data vars   queue ElementAt i  vars                                 data status   1                                 data misc   queue ElementAt i  misc                                 data filenameOrSavePath   queue ElementAt i  filenameOrSavePath                                 queue i    data                                 queueBWorker shtIndex    i                                 dataStatistics shtIndex     New  data statistics                                   bwDataRequest shtIndex  RunWorkerAsync queue i                                   Threading Thread Sleep 50                              End If                         End SyncLock                     End If                 Next i             Next shtIndex         End While         sendToQueue   False     End Sub      Public Function QueuesToSend queue As List Of  queue data struct   As Integer         Dim counter As Integer   0         For i   0 To queue Count - 1             If queue i  status Equals 0  Then                 counter    1             End If         Next i         Return counter     End Function     Public Function QueuesToComplete queue As List Of  queue data struct   As Integer         Dim counter As Integer   0         For i   0 To queue Count - 1             If queue i  status Equals 1  Then                 counter    1             End If         Next i         Return counter     End Function     Public Function QueuesMultiHash queue As List Of  queue data struct   As Integer         Dim counter As Integer   0         For i   0 To queue Count - 1             If queue i  status Equals 1  Then                 counter    i             End If         Next i         Return counter     End Function      Public Function IsBase64String ByVal s As String  As Boolean         s   s Trim           Return  s Length Mod 4   0  AndAlso Regex IsMatch s   quot   a-zA-Z0-9       0 3   quot   RegexOptions None      End Function                                                                                                                                                                           Public Function ConvertDataToArray key As String  fields As String    response As String  As Dictionary Of String  List Of String           If GetMessage response  Equals  quot 1001 quot   Then             Threading Thread CurrentThread CurrentUICulture   Globalization CultureInfo GetCultureInfo state currentLang              errorMessage    quot   error  true  message    quot   amp  My Resources strings errorNoRecordsFound  amp   quot    quot              Return Nothing         End If         Try             Dim jsonResult   JsonConvert DeserializeObject Of Dictionary Of String  Object   response              If jsonResult ContainsKey key  Then                 If Not jsonResult Item key  item 0  Count Equals fields Length  Then                     Threading Thread CurrentThread CurrentUICulture   Globalization CultureInfo GetCultureInfo state currentLang                      errorMessage    quot   error  true  message    quot   amp  My Resources strings JsonFieldsMismatch  amp   quot   table  quot   amp  key  amp   quot    quot                      Return Nothing                 Else                     Dim results   New Dictionary Of String  List Of String                       For k   0 To fields Length - 1                         Dim fieldValues As List Of String    New List Of String                          For i   0 To jsonResult Item key  Count - 1                             fieldValues Add jsonResult Item key  item i  item k  ToString                          Next i                         results Add fields k   fieldValues                       Next k                     Return results                 End If             Else                 Threading Thread CurrentThread CurrentUICulture   Globalization CultureInfo GetCultureInfo state currentLang                  errorMessage    quot   error  true  message    quot   amp  My Resources strings JsonkeyNotFound  amp   quot    quot   amp  key  amp   quot    quot                  Return Nothing             End If         Catch ex As Exception             errorMessage    quot   error  true  message    quot   amp  ex ToString  amp   quot    quot              errorMessage   ex ToString             Return Nothing         End Try     End Function End Class  the AeonLabs Envoriment is a class with a collection or fields and properties  And the one bellow is for making a POST request  Imports System ComponentModel Imports System IO Imports System Net Imports System Text Imports System Web Imports System Web Script Serialization Imports System Windows Forms Imports AeonLabs Environment Imports AeonLabs Security  Public Class HttpDataPostData     Inherits HttpDataCore      Public Event updateProgress sender As Object  misc As Dictionary Of String  String       Public Event dataArrived sender As Object  requestData As String  misc As Dictionary Of String  String        Public Sub New ByVal Optional  state As environmentVarsCore   Nothing  ByVal Optional  url As String    quot  quot           MyBase New  state   url      End Sub     Public Sub initialize ByVal Optional  threadCount As Integer   0          If Not  threadCount Equals 0  Then             threadCount    threadCount         End If          ReDim bwDataRequest threadCount          ReDim queueBWorker threadCount           For shtIndex   0 To threadCount             dataStatistics Add New  data statistics               bwDataRequest shtIndex    New System ComponentModel BackgroundWorker             bwDataRequest shtIndex  WorkerReportsProgress   True             bwDataRequest shtIndex  WorkerSupportsCancellation   True              AddHandler bwDataRequest shtIndex  DoWork  AddressOf bwDataRequest DoWork             AddHandler bwDataRequest shtIndex  RunWorkerCompleted  AddressOf bwDataRequest RunWorkerCompleted         Next shtIndex         Dim retry As  retry attempts         With retry              counter   0              previousPattern   -1              pattern   0              errorMessage    quot  quot          End With         retryAttempts   retry     End Sub      Private Sub bwDataRequest DoWork ByVal sender As System Object  ByVal e As System ComponentModel DoWorkEventArgs             Find out the Index of the bWorker that called this DoWork  could be cleaner  I know          Dim Y As Integer         Dim Index As Integer   Nothing         For Y   0 To UBound bwDataRequest              If sender Equals bwDataRequest Y   Then                 Index   Y                 Exit For             End If         Next Y          Dim queue As  queue data struct         queue   e Argument          Dim vars As New Dictionary Of String  String          vars   queue vars           TODO translation need to be local         If Not System Net NetworkInformation NetworkInterface GetIsNetworkAvailable   Then             Threading Thread CurrentThread CurrentUICulture   System Globalization CultureInfo GetCultureInfo state currentLang              e Result    quot   error  true  message    quot   amp  My Resources strings errorNoNetwork  amp   quot    quot              Exit Sub         End If         If vars Is Nothing Then             e Result    quot   error  true  message   missconfiguration vars   quot              Exit Sub         End If          If Not vars ContainsKey  quot id quot   Then             vars Add  quot id quot   state userId          End If         If Not vars ContainsKey  quot pid quot   Then             Dim appId As New FingerPrint             vars Add  quot pid quot   appId Value          End If         If Not vars ContainsKey  quot language quot   Then             vars Add  quot language quot   state currentLang          End If         If Not vars ContainsKey  quot origin quot   Then             vars Add  quot origin quot   state softwareAccessMode          End If          Dim serializer As New JavaScriptSerializer           Dim json As String   serializer Serialize vars          Dim encryption As New AesCipher state          Dim encrypted As String   HttpUtility UrlEncode encryption encrypt json           Dim PostData    quot origin  quot   amp  state softwareAccessMode  amp   quot  amp data  quot   amp  encrypted         Dim request As WebRequest   WebRequest Create url          Dim responseFromServer As String    quot  quot          Dim decrypted As String    quot  quot           request Method    quot POST quot          Dim byteArray As Byte     Encoding UTF8 GetBytes PostData          request ContentType    quot application x-www-form-urlencoded quot          request Headers Add  quot Authorization quot   state ApiHttpHeaderToken  amp   quot - quot   amp  state softwareAccessMode          request ContentLength   byteArray Length         Try             Dim dataStream As Stream   request GetRequestStream               dataStream Write byteArray  0  byteArray Length              dataStream Close               Dim response As HttpWebResponse   CType request GetResponse    HttpWebResponse              dataStream   response GetResponseStream               Dim reader As New StreamReader dataStream              responseFromServer   reader ReadToEnd               reader Close               dataStream Close               response Close                If response StatusCode   HttpStatusCode Accepted Or response StatusCode   200 Then                 If IsBase64String responseFromServer  And Not responseFromServer Equals  quot  quot   Then                     decrypted   encryption decrypt  responseFromServer   Replace  quot    quot    quot   quot                   Else                     Threading Thread CurrentThread CurrentUICulture   System Globalization CultureInfo GetCultureInfo state currentLang                      decrypted    quot   error  true  encrypted  false  message    quot   amp  My Resources strings contactingCommServer  amp   quot    quot   amp  responseFromServer  amp   quot     quot                  End If             Else                 Threading Thread CurrentThread CurrentUICulture   System Globalization CultureInfo GetCultureInfo state currentLang                  decrypted    quot   error  true  message    quot   amp  My Resources strings contactingCommServer  amp   quot    quot   amp  response StatusCode  amp   quot      statuscode    quot   amp  response StatusCode  amp   quot    quot              End If         Catch ex As Exception             Threading Thread CurrentThread CurrentUICulture   System Globalization CultureInfo GetCultureInfo state currentLang              decrypted    quot   error  true  message    quot   amp  My Resources strings contactingCommServer  amp   quot    quot   amp  ex Message ToString Replace  quot   quot    quot    quot    amp   quot     quot          End Try          e Result   decrypted Replace  quot    quot    quot   quot       End Sub      Private Sub bwDataRequest RunWorkerCompleted ByVal sender As Object  ByVal e As System ComponentModel RunWorkerCompletedEventArgs            Find out the Index of the bWorker that called this DoWork  could be cleaner  I know          Dim Y As Integer         Dim Index As Integer   Nothing         Dim data As New  queue data struct          For Y   0 To UBound bwDataRequest              If sender Equals bwDataRequest Y   Then                 Index   Y                 Exit For             End If         Next Y          If IsResponseOk e Result   quot statuscode quot   Then             data   New  queue data struct             data   queue queueBWorker Index               data status   0  re queue the file             SyncLock queueLock                 queue queueBWorker Index     data             End SyncLock             Dim errorMsg As String   GetMessage e Result              Dim retry As  retry attempts             With retry                  counter   retryAttempts counter                  previousPattern   retryAttempts previousPattern                  pattern   retryAttempts pattern                  errorMessage   retryAttempts errorMessage             End With             retry errorMessage   If retryAttempts errorMessage IndexOf errorMsg   gt  -1  retryAttempts errorMessage  retryAttempts errorMessage  amp  System Environment NewLine  amp  errorMsg               retry pattern   QueuesMultiHash queue              If retry previousPattern Equals retry pattern  Then                 retry counter    1             Else                 retry counter   1                 retry previousPattern   retryAttempts pattern             End If              retryAttempts   retry             Exit Sub         End If          data   New  queue data struct         data   queue queueBWorker Index           data status   -1  completed sucessfully status         SyncLock queueLock             queue queueBWorker Index     data         End SyncLock          loadingCounter    1         CompletionPercentage    loadingCounter   queue Count    100         statusMessage    quot Loading data from the cloud     quot          RaiseEvent updateProgress Me  queue queueBWorker Index   misc          RaiseEvent dataArrived Me  e Result  queue queueBWorker Index   misc      End Sub End Class  The Aoenlabs Security is a class for sending POST data encrypted using standard encryption algorithms

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You can also use Postman App for Windows  Linux or OSX  It is a complete web app  amp  service test environment that involve all the request methods  You can find the latest version here

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MSDN has a sample   using System  using System IO  using System Net  using System Text   namespace Examples System Net       public class WebRequestPostExample               public static void Main                            Create a request using a URL that can receive a post               WebRequest request   WebRequest Create  http   www contoso com PostAccepter aspx                   Set the Method property of the request to POST              request Method    POST                  Create POST data and convert it to a byte array              string postData    This is a test that posts this string to a Web server                byte   byteArray   Encoding UTF8 GetBytes postData                  Set the ContentType property of the WebRequest              request ContentType    application x-www-form-urlencoded                  Set the ContentLength property of the WebRequest              request ContentLength   byteArray Length                 Get the request stream              Stream dataStream   request GetRequestStream                   Write the data to the request stream              dataStream Write byteArray  0  byteArray Length                  Close the Stream object              dataStream Close                   Get the response              WebResponse response   request GetResponse                   Display the status              Console WriteLine   HttpWebResponse response  StatusDescription                  Get the stream containing content returned by the server              dataStream   response GetResponseStream                   Open the stream using a StreamReader for easy access              StreamReader reader   new StreamReader dataStream                  Read the content              string responseFromServer   reader ReadToEnd                   Display the content              Console WriteLine responseFromServer                  Clean up the streams              reader Close                dataStream Close                response Close

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In  net core you can make post-call with following code  here I added some extra features to this code so can make your code work behind a proxy and with network credentials if any  also here I mention that you can change the encoding of your message   I hope this explains all and help you in coding   HttpClient client   GetHttpClient  config            if  headers    null                        foreach  var header in headers                                client DefaultRequestHeaders TryAddWithoutValidation header Key  header Value                                    client BaseAddress   new Uri baseAddress            Encoding encoding   Encoding UTF8            var result   await client PostAsync url  new StringContent body  encoding   application json    ConfigureAwait false           if  result IsSuccessStatusCode                        return new RequestResponse   severity    Success   httpResponse   result Content ReadAsStringAsync   Result  StatusCode   result StatusCode                      else                       return new RequestResponse   severity    failure   httpResponse   result Content ReadAsStringAsync   Result  StatusCode   result StatusCode                 public HttpClient GetHttpClient IConfiguration  config                        bool ProxyEnable   Convert ToBoolean  config  GlobalSettings ProxyEnable                  HttpClient client   null              if   ProxyEnable                                client   new HttpClient                              else                               string ProxyURL    config  GlobalSettings ProxyURL                    string ProxyUserName    config  GlobalSettings ProxyUserName                    string ProxyPassword    config  GlobalSettings ProxyPassword                    string   ExceptionURL    config  GlobalSettings ExceptionURL   Split                       bool BypassProxyOnLocal   Convert ToBoolean  config  GlobalSettings BypassProxyOnLocal                     bool UseDefaultCredentials   Convert ToBoolean  config  GlobalSettings UseDefaultCredentials                      WebProxy proxy   new WebProxy                                       Address   new Uri ProxyURL                       BypassProxyOnLocal   BypassProxyOnLocal                      UseDefaultCredentials   UseDefaultCredentials                      BypassList   ExceptionURL                      Credentials   new NetworkCredential ProxyUserName  ProxyPassword                                       HttpClientHandler handler   new HttpClientHandler   Proxy   proxy                    client   new HttpClient handler true                             return client

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This is a complete working example of sending receiving data in JSON format  I used Visual Studio 2013 Express Edition   using System  using System Collections Generic  using System Data  using System Data OleDb  using System IO  using System Linq  using System Net Http  using System Text  using System Threading Tasks  using System Web Script Serialization   namespace ConsoleApplication1       class Customer               public string Name   get  set            public string Address   get  set            public string Phone   get  set               public class Program               private static readonly HttpClient  Client   new HttpClient            private static JavaScriptSerializer  Serializer   new JavaScriptSerializer             static void Main string   args                        Run   Wait                       static async Task Run                         string url    http   www example com api Customer               Customer cust   new Customer     Name    Example Customer   Address    Some example address   Phone    Some phone number                 var json    Serializer Serialize cust               var response   await Request HttpMethod Post  url  json  new Dictionary lt string  string gt                  string responseText   await response Content ReadAsStringAsync                 List lt YourCustomClassModel gt  serializedResult    Serializer Deserialize lt List lt YourCustomClassModel gt  gt  responseText                Console WriteLine responseText               Console ReadLine                            lt summary gt              Makes an async HTTP Request              lt  summary gt               lt param name  pMethod  gt Those methods you know  GET  POST  HEAD  etc    lt  param gt               lt param name  pUrl  gt Very predictable    lt  param gt               lt param name  pJsonContent  gt String data to POST on the server lt  param gt               lt param name  pHeaders  gt If you use some kind of Authorization you should use this lt  param gt               lt returns gt  lt  returns gt          static async Task lt HttpResponseMessage gt  Request HttpMethod pMethod  string pUrl  string pJsonContent  Dictionary lt string  string gt  pHeaders                        var httpRequestMessage   new HttpRequestMessage                httpRequestMessage Method   pMethod              httpRequestMessage RequestUri   new Uri pUrl               foreach  var head in pHeaders                                httpRequestMessage Headers Add head Key  head Value                             switch  pMethod Method                                case  POST                       HttpContent httpContent   new StringContent pJsonContent  Encoding UTF8   application json                        httpRequestMessage Content   httpContent                      break                              return await  Client SendAsync httpRequestMessage

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Simple  one-liner  no error checking  no wait for response  solution I ve found so far    new WebClient    UploadStringAsync new Uri Address   dataString      Use with caution

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If you like a fluent API you can use Tiny RestClient  It s available at NuGet   var client   new TinyRestClient new HttpClient     http   MyAPI com api       POST var city   new City     Name    Paris   Country    France        With content var response   await client PostRequest  City   city                              ExecuteAsync lt bool gt

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When using Windows Web Http namespace  for POST instead of FormUrlEncodedContent  we write  HttpFormUrlEncodedContent  Also the response is type of HttpResponseMessage  The rest is as Evan Mulawski wrote down

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This solution uses nothing but standard  NET calls   Tested    In use in an enterprise WPF application  Uses async await to avoid blocking the UI  Compatible with  NET 4 5   Tested with no parameters  requires a  GET  behind the scenes   Tested with parameters  requires a  POST  behind the scenes   Tested with a standard web page such as Google  Tested with an internal Java-based webservice    Reference      Add a Reference to the assembly System Web   Code   using System  using System Collections Generic  using System Collections Specialized  using System Net  using System Net Http  using System Threading Tasks  using System Web   private async Task lt WebResponse gt  CallUri string url  TimeSpan timeout        var uri   new Uri url       NameValueCollection rawParameters   HttpUtility ParseQueryString uri Query       var parameters   new Dictionary lt string  string gt         foreach  string p in rawParameters Keys                parameters p    rawParameters p              var client   new HttpClient   Timeout   timeout        HttpResponseMessage response      if  parameters Count    0                response   await client GetAsync url             else               var content   new FormUrlEncodedContent parameters           string urlMinusParameters   uri OriginalString Split      0      Parameters always follow the     symbol          response   await client PostAsync urlMinusParameters  content             var responseString   await response Content ReadAsStringAsync         return new WebResponse response StatusCode  responseString      private class WebResponse       public WebResponse HttpStatusCode httpStatusCode  string response                this HttpStatusCode   httpStatusCode          this Response   response            public HttpStatusCode HttpStatusCode   get        public string Response   get        To call with no parameters  uses a  GET  behind the scenes     var timeout   TimeSpan FromSeconds 300    WebResponse response   await this CallUri  http   www google com    timeout    if  response HttpStatusCode    HttpStatusCode OK          Console Write response Response      Print HTML       To call with parameters  uses a  POST  behind the scenes     var timeout   TimeSpan FromSeconds 300    WebResponse response   await this CallUri  http   example com path to page name ferret amp color purple   timeout    if  response HttpStatusCode    HttpStatusCode OK          Console Write response Response      Print HTML

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There are several ways to perform HTTP GET and POST requests     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      POST  var values   new Dictionary lt string  string gt           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     GET  var responseString   await client GetStringAsync  http   www example com recepticle aspx         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 lt Person gt  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       POST  var responseString   await  http   www example com recepticle aspx       PostUrlEncodedAsync new   thing1    hello   thing2    world          ReceiveString     GET  var responseString   await  http   www example com recepticle aspx       GetStringAsync         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      POST  var request    HttpWebRequest WebRequest Create  http   www example com recepticle aspx     var postData    thing1     Uri EscapeDataString  hello        postData      amp 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     GET  var request    HttpWebRequest WebRequest Create  http   www example com recepticle aspx     var response    HttpWebResponse request GetResponse     var responseString   new StreamReader response GetResponseStream    ReadToEnd         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       POST  using  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      GET  using  var client   new WebClient          var responseString   client DownloadString  http   www example com recepticle aspx

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POST request in itself means sending information in the body  I found a fairly simple way to do this  Use Postman by Google  which allows you to specify the content-type a header field  as application json and then provide name-value pairs as parameters  Just use your url in the place of theirs  POST var responseString   await  quot http   www example com recepticle aspx quot       PostUrlEncodedAsync new   thing1    quot hello quot   thing2    quot world quot          ReceiveString     GET var responseString   await  quot http   www example com recepticle aspx quot       GetStringAsync

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Yet another way of doing it  using  HttpClient httpClient   new HttpClient    using  MultipartFormDataContent form   new MultipartFormDataContent          form Add new StringContent param1    quot param1 quot        form Add new StringContent param2    quot param2 quot        using  HttpResponseMessage response   await httpClient PostAsync url  form                 response EnsureSuccessStatusCode            string res   await response Content ReadAsStringAsync            return res           This way you can easily post a stream

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There are some really good answers on here  Let me post a different way to set your headers with the WebClient    I will also show you how to set an API key           var client   new WebClient            string credentials   Convert ToBase64String Encoding ASCII GetBytes userName         passWord            client Headers HttpRequestHeader Authorization      Basic  credentials              If you have your data stored in an object serialize it into json to pass to the webclient with Newtonsoft s JsonConvert         var encodedJson   JsonConvert SerializeObject newAccount            client Headers Add   x-api-key  ApiKey             client Headers Add  Content-Type application json            try                       var response   client UploadString    apiurl    encodedJson                 if you have a model to deserialize the json into Newtonsoft will help bind the data to the model  this is an extremely useful trick for GET calls when you have a lot of data  you can strongly type a model and dump it into an instance of that class              Response response1   JsonConvert DeserializeObject lt Response gt  response

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Simple GET request  using System Net        using  var wb   new WebClient          var response   wb DownloadString url       Simple POST request  using System Net  using System Collections Specialized        using  var wb   new WebClient          var data   new NameValueCollection        data  username      myUser       data  password      myPassword        var response   wb UploadValues url   POST   data       string responseInString   Encoding UTF8 GetString response

[c#] How to make an HTTP POST web request

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