---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_USERNAME
Section: 3
Source: libcurl
See-also:
  - CURLOPT_HTTPAUTH (3)
  - CURLOPT_PASSWORD (3)
  - CURLOPT_PROXYAUTH (3)
  - CURLOPT_USERPWD (3)
Protocol:
  - All
Added-in: 7.19.1
---

# NAME

CURLOPT_USERNAME - username to use in authentication

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_USERNAME,
                          char *username);
~~~

# DESCRIPTION

Pass a char pointer as parameter, which should be pointing to the
null-terminated username to use for the transfer.

CURLOPT_USERNAME(3) sets the username to be used in protocol authentication.
You should not use this option together with the (older) CURLOPT_USERPWD(3)
option.

When using Kerberos V5 authentication with a Windows based server, you should
include the domain name in order for the server to successfully obtain a
Kerberos Ticket. If you do not then the initial part of the authentication
handshake may fail.

When using NTLM, the username can be specified without the domain name should
the server be part of a single domain and forest.

To include the domain name use either Down-Level Logon Name or UPN (User
Principal Name) formats. For example, **EXAMPLE\user** and
**user@example.com** respectively.

Some HTTP servers (on Windows) support inclusion of the domain for Basic
authentication as well.

To specify the password and login options, along with the username, use the
CURLOPT_PASSWORD(3) and CURLOPT_LOGIN_OPTIONS(3) options.

The application does not have to keep the string around after setting this
option.

For some authentication methods (`Negotiate`, or `NTLM` when built to use
SSPI), setting it to a zero-length string (`""`) makes libcurl use an implied
*ambient* user decided by the environment. libcurl cannot identify this user
and may reuse an authenticated connection for a later transfer on the same
easy handle. If the ambient user changes while that connection remains
reusable, the later transfer can be authenticated as the previous user.
Applications must prevent such reuse when changing ambient users.

# DEFAULT

NULL

# %PROTOCOLS%

# EXAMPLE

~~~c
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");

    curl_easy_setopt(curl, CURLOPT_USERNAME, "clark");

    result = curl_easy_perform(curl);

    curl_easy_cleanup(curl);
  }
}
~~~

# %AVAILABILITY%

# RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
libcurl-errors(3).
