How to login to Instagram website using IdHTTP in

I am trying to login to instagram website using idhttp in Delphi. I used google chrome developer tools to get the data and this is what I've tried so far..

procedure TForm1.Button1Click(Sender: TObject);
var
  lHTTP: TIdHTTP;
  S,M : TStrings;
  IdSSL: TIdSSLIOHandlerSocketOpenSSL;
begin
  S := TStringList.Create;
  S.Add('username :' +Edit1.Text);
  S.Add('password :'+ Edit2.Text);
  lHTTP := TIdHTTP.Create(nil);
  lHTTP.ReadTimeout := 30000;
  lHTTP.HandleRedirects := True;
  IdSSL := TIdSSLIOHandlerSocketOpenSSL.Create(lHTTP);
  IdSSL.SSLOptions.Method := sslvTLSv1;
  IdSSL.SSLOptions.Mode := sslmClient;
  lHTTP.IOHandler := IdSSL;
  lHTTP.Request.CustomHeaders.Add('x-csrftoken:'+ Edit3.Text);
  lHTTP.Request.CustomHeaders.Add('x-instagram-ajax:1');
  lHTTP.Request.CustomHeaders.Add(' x-requested-with:XMLHttpRequest');
  lHTTP.Request.CustomHeaders.Add('referer:https://www.instagram.com/');
  lHTTP.Request.ContentType := 'application/x-www-form-urlencoded';
  lHTTP.Request.UserAgent := 'Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.76 Mobile Safari/537.36';
  lHTTP.Post('https://www.instagram.com/accounts/login/ajax/', S);
  Memo1.Lines.Add(lHTTP.Request.ToString);
end;

I get the access token manually for now, just to test the code. I get HTTP/1.1 403 Forbidden. !

UPDATE

This is the cookies information..

Response Headers
set-cookie:csrftoken=e3YbQ1FobxgMGcLHRAkj****ML97psae; expires=Tue, 20-Jun-2017 19:09:21 GMT; Max-Age=31449600; Path=/
set-cookie:s_network=; expires=Tue, 21-Jun-2016 20:09:21 GMT; Max-Age=3600; Path=/
set-cookie:sessionid=IGSC3074cea6684a55981cc30d3c5222ed9e4675db0aa4665d3f5b7ed4ae09be01b6%3AugN5uNRztrtVarx6LuheBkv5tNuaVHrL%3A%7B%22_token_ver%22%3A2%2C%22_auth_user_id%22%3A348733484%2C%22_token%22%3A%22348733484%3A6dXogo2jTCkOf29JEUxHavzxqp9iUOr4%3Aa4f855cabbd5c5d2999538a8ec9093c6a59af65e7306998a5647341bdd691158%22%2C%22asns%22%3A%7B%225.37.149.220%22%3A28885%2C%22time%22%3A1466536160%7D%2C%22_auth_user_backend%22%3A%22accounts.backends.CaseInsensitiveModelBackend%22%2C%22last_refreshed%22%3A1466536160.338314%2C%22_platform%22%3A4%2C%22_auth_user_hash%22%3A%22%22%7D; expires=Mon, 19-Sep-2016 19:09:21 GMT; httponly; Max-Age=7776000; Path=/
set-cookie:ds_user_id=348733***; expires=Mon, 19-Sep-2016 19:09:21 GMT; Max-Age=


Request Headers
set-cookie:sessionid=IGSC3074cea6684a55981cc30d3c5222ed9e4675db0aa4665d3f5b7ed4ae09be01b6%3AugN5uNRztrtVarx6LuheBkv5tNuaVHrL%3A%7B%22_token_ver%22%3A2%2C%22_auth_user_id%22%3A348***484%2C%22_token%22%3A%22348733484%3A6dXogo2jTCkOf29JEUxHavzxqp9iUOr4%3Aa4f855cabbd5c5d2999538a8ec9093c6a59af65e7306998a5647341bdd691158%22%2C%22asns%22%3A%7B%225.37.149.220%22%3A28885%2C%22time%22%3A1466536160%7D%2C%22_auth_user_backend%22%3A%22accounts.backends.CaseInsensitiveModelBackend%22%2C%22last_refreshed%22%3A1466536160.338314%2C%22_platform%22%3A4%2C%22_auth_user_hash%22%3A%22%22%7D; expires=Mon, 19-Sep-2016 19:09:21 GMT; httponly; Max-Age=7776000; Path=/
set-cookie:ds_user_id=348733***; expires=Mon, 19-Sep-2016 19:09:21 GMT; Max-Age=7776000; Path=/

You are not populating the TStringList correctly. You need to use = instead of : as the name=value delimiter. Same with CustomHeaders.Add(). In the latter case, I would suggest using CustomHeaders.Values[] instead.

You also should be using the Request.Referer property instead of CustomHeaders.Add().

It is not uncommon to need to first request the HTML page that contains the login form before submitting the actual login, so that any cookies associated with the HTML can be captured and submitted with the login form. Instagram is no different.

Also, Request.ToString() is meaningless, you should not be using that at all.

And lastly, you are leaking the objects that you create.

With that said, try this instead:

procedure TForm1.Button1Click(Sender: TObject);
var
  lHTTP: TIdHTTP;
  IdSSL: TIdSSLIOHandlerSocketOpenSSL;
  Params : TStrings;
  Reply, Token: string;
  Cookie: TIdCookie;
begin
  Params := TStringList.Create;
  try
    Params.Add('username=' + Edit1.Text);
    Params.Add('password=' + Edit2.Text);

    lHTTP := TIdHTTP.Create(nil);
    try
      IdSSL := TIdSSLIOHandlerSocketOpenSSL.Create(lHTTP);
      IdSSL.SSLOptions.Method := sslvTLSv1;
      IdSSL.SSLOptions.Mode := sslmClient;
      lHTTP.IOHandler := IdSSL;

      lHTTP.ReadTimeout := 30000;
      lHTTP.HandleRedirects := True;

      // capture cookies first...
      // passing nil to ignore any response body data and not waste memory for it...
      lHTTP.Request.UserAgent := 'Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.76 Mobile Safari/537.36';
      lHTTP.Get('https://www.instagram.com', TStream(nil));

      Cookie := lHTTP.CookieManager.CookieCollection.Cookie['csrftoken', 'www.instagram.com'];
      if Cookie <> nil then
        Token := Cookie.Value;

      // now submit the login webform...
      lHTTP.Request.CustomHeaders.Values['X-CSRFToken'] := Token;
      lHTTP.Request.CustomHeaders.Values['X-Instagram-AJAX'] := '1';
      lHTTP.Request.CustomHeaders.Values['X-Requested-With'] := 'XMLHttpRequest';
      lHTTP.Request.Referer := 'https://www.instagram.com/';
      lHTTP.Request.ContentType := 'application/x-www-form-urlencoded';
      lHTTP.Request.UserAgent := 'Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.76 Mobile Safari/537.36';
      Reply := lHTTP.Post('https://www.instagram.com/accounts/login/ajax/', Params);

      Memo1.Text := Reply;
    finally
      lHTTP.Free;
    end;
  finally
    Params.Free;
  end;
end;

Here is the resulting HTTP dialog for the two requests ¹:

¹: I don't have an Instagram account, which is why the login is not authenticated in this example. But as you can see below, the code is still able to receive an HTTP 200 response with JSON data from the login POST.

GET / HTTP/1.1
Host: www.instagram.com
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
User-Agent: Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.76 Mobile Safari/537.36

HTTP/1.1 200 OK
Strict-Transport-Security: max-age=86400
Content-Language: en
Set-Cookie: sessionid=; expires=Thu, 01-Jan-1970 00:00:00 GMT; Max-Age=0; Path=/; HttpOnly; Domain=instagram.com
Expires: Sat, 01 Jan 2000 00:00:00 GMT
Vary: Cookie, Accept-Language, Accept-Encoding
Pragma: no-cache
Cache-Control: private, no-cache, no-store, must-revalidate
Date: Tue, 21 Jun 2016 20:06:56 GMT
X-Frame-Options: SAMEORIGIN
Content-Type: text/html
Set-Cookie: csrftoken=<token>; expires=Tue, 20-Jun-2017 20:06:56 GMT; Max-Age=31449600; Path=/
Set-Cookie: mid=<value>; expires=Mon, 16-Jun-2036 20:06:56 GMT; Max-Age=630720000; Path=/
Connection: keep-alive
Content-Length: <HTML byte length>

<actual HTML bytes>

POST /accounts/login/ajax/ HTTP/1.0
Content-Type: application/x-www-form-urlencoded
Content-Length: <params byte length>
X-CSRFToken: <token>
X-Instagram-AJAX: 1
X-Requested-With: XMLHttpRequest
Host: www.instagram.com
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Referer: https://www.instagram.com/
User-Agent: Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.76 Mobile Safari/537.36
Cookie: mid=<value>; csrftoken=<token>

username=<user>&password=<pass>

HTTP/1.1 200 OK
Strict-Transport-Security: max-age=86400
Content-Language: en
Expires: Sat, 01 Jan 2000 00:00:00 GMT
Vary: Cookie, Accept-Language
Pragma: no-cache
Cache-Control: private, no-cache, no-store, must-revalidate
Date: Tue, 21 Jun 2016 20:06:57 GMT
Content-Type: application/json
Set-Cookie: csrftoken=<token>; expires=Tue, 20-Jun-2017 20:06:57 GMT; Max-Age=31449600; Path=/
Connection: close
Content-Length: <json byte length>

{"status": "ok", "authenticated": false, "user": "<user>"}