---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: curl_version_info
Section: 3
Source: libcurl
See-also:
  - curl_version (3)
Protocol:
  - All
Added-in: 7.10
---

# NAME

curl_version_info - returns runtime libcurl version info

# SYNOPSIS

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

curl_version_info_data *curl_version_info(CURLversion age);
~~~

# DESCRIPTION

Returns a pointer to a filled in static struct with information about various
features in the running version of libcurl. The input argument *age* has no
use and we recommend you set it to `CURLVERSION_NOW`.

This function may alter the returned static data as long as
curl_global_init(3) has not been called. It is therefore not thread-safe
before libcurl initialization occurs.

The curl_version_info_data struct looks like this

~~~c
typedef struct {
  CURLversion age;          /* see description below */

  const char *version;      /* human readable string */
  unsigned int version_num; /* numeric representation */
  const char *host;         /* human readable string */
  int features;             /* bitmask, see below */
  char *ssl_version;        /* human readable string */
  long ssl_version_num;     /* not used, always zero */
  const char *libz_version; /* human readable string */
  const char *const *protocols; /* protocols */

  /* when 'age' is CURLVERSION_SECOND or higher, the members below exist */
  const char *ares;         /* human readable string */
  int ares_num;             /* number */

  /* when 'age' is CURLVERSION_THIRD or higher, the members below exist */
  const char *libidn;       /* human readable string */

  /* when 'age' is CURLVERSION_FOURTH or higher (>= 7.16.1), the members
     below exist */
  int iconv_ver_num;       /* '_libiconv_version' if iconv support enabled */

  const char *libssh_version; /* human readable string */

  /* when 'age' is CURLVERSION_FIFTH or higher (>= 7.57.0), the members
     below exist */
  unsigned int brotli_ver_num; /* Numeric Brotli version
                                  (MAJOR << 24) | (MINOR << 12) | PATCH */
  const char *brotli_version; /* human readable string. */

  /* when 'age' is CURLVERSION_SIXTH or higher (>= 7.66.0), the members
     below exist */
  unsigned int nghttp2_ver_num; /* Numeric nghttp2 version
                                   (MAJOR << 16) | (MINOR << 8) | PATCH */
  const char *nghttp2_version; /* human readable string. */

  const char *quic_version;    /* human readable quic (+ HTTP/3) library +
                                  version or NULL */

  /* when 'age' is CURLVERSION_SEVENTH or higher (>= 7.70.0), the members
     below exist */
  const char *cainfo;          /* the built-in default CURLOPT_CAINFO, might
                                  be NULL */
  const char *capath;          /* the built-in default CURLOPT_CAPATH, might
                                  be NULL */
  /* when 'age' is CURLVERSION_EIGHTH or higher (>= 7.71.0), the members
     below exist */
  unsigned int zstd_ver_num; /* Numeric Zstd version
                                  (MAJOR << 24) | (MINOR << 12) | PATCH */
  const char *zstd_version; /* human readable string. */
  /* when 'age' is CURLVERSION_NINTH or higher (>= 7.75.0), the members
     below exist */
  const char *hyper_version; /* human readable string. */
  /* when 'age' is CURLVERSION_TENTH or higher (>= 7.77.0), the members
     below exist */
  const char *gsasl_version; /* human readable string. */
  /* when 'age' is CURLVERSION_ELEVENTH or higher (>= 7.87.0), the members
     below exist */
  const char *const *feature_names; /* Feature names. */
  /* when 'age' is CURLVERSION_TWELFTH or higher (>= 8.8.0), the members
     below exist */
  const char *const *rtmp_version; /* human readable string */
} curl_version_info_data;
~~~

*age* describes what the age of this struct is. That number is different
depending on how recent your libcurl is. The documentation above describes
which struct fields that were added at which age. Trying to access a struct
field that is newer than the age of your struct may cause undefined behavior
and possibly crashes.

*version* is an ASCII string for the libcurl version.

*version_num* is a 24-bit number created like this: \<8 bits major number\> |
\<8 bits minor number\> | \<8 bits patch number\>. Version 7.9.8 is therefore
returned as 0x070908.

*host* is an ASCII string showing what host information that this libcurl
was built for. As discovered by a configure script or set by the build
environment.

*features* is a bit mask representing available features. It can have none,
one or more bits set. The use of this field is deprecated: use
*feature_names* instead. The feature names description below lists the
associated bits.

*feature_names* is a pointer to an array of string pointers, containing the
names of the features that libcurl supports. The array is terminated by a NULL
entry. See the list of features names below.

*ssl_version* is an ASCII string for the TLS library name + version used. If
libcurl has no SSL support, this is NULL. For example "Schannel", "Secure
Transport" or "OpenSSL/1.1.0g". For MultiSSL builds the string contains all
SSL backend names and the inactive backend names are in parentheses. For
example "(OpenSSL/3.0.8) Schannel" or "OpenSSL/3.0.8 (Schannel)".

*ssl_version_num* is always 0.

*libz_version* is an ASCII string (there is no numerical version). If
libcurl has no libz support, this is NULL.

*protocols* is a pointer to an array of char * pointers, containing the
names protocols that libcurl supports (using lowercase letters). The protocol
names are the same as would be used in URLs. The array is terminated by a NULL
entry.

# FEATURES

## `alt-svc`

*features* mask bit: CURL_VERSION_ALTSVC

HTTP Alt-Svc parsing and the associated options (Added in 7.64.1)

## `AppleSecTrust`

*features* mask bit: non-existent

libcurl was built with support for Apple's SecTrust service to verify
server certificates (Added in 8.17.0).

## `AsynchDNS`

*features* mask bit: CURL_VERSION_ASYNCHDNS

libcurl was built with support for asynchronous name lookups, which allows
more exact timeouts (even on Windows) and less blocking when using the multi
interface.

## `brotli`

*features* mask bit: CURL_VERSION_BROTLI

supports HTTP Brotli content encoding using libbrotlidec

## `asyn-rr`

*features* mask bit: non-existent

libcurl was built to use c-ares for EXPERIMENTAL HTTPS resource record
resolves, but uses the threaded resolver for "normal" resolves (Added in
8.12.0)

## `Debug`

*features* mask bit: CURL_VERSION_DEBUG

libcurl was built with debug capabilities

## `ECH`

*features* mask bit: non-existent

libcurl was built with ECH support (experimental, added in 8.8.0)

## `gsasl`

*features* mask bit: CURL_VERSION_GSASL

libcurl was built with libgsasl and thus with some extra SCRAM-SHA
authentication methods. (added in 7.76.0)

## `GSS-API`

*features* mask bit: CURL_VERSION_GSSAPI

libcurl was built with support for GSS-API. This makes libcurl use provided
functions for Kerberos and SPNEGO authentication. It also allows libcurl
to use the current user credentials without the app having to pass them on.

## `HSTS`

*features* mask bit: CURL_VERSION_HSTS

libcurl was built with support for HSTS (HTTP Strict Transport Security)
(Added in 7.74.0)

## `HTTP2`

*features* mask bit: CURL_VERSION_HTTP2

libcurl was built with support for HTTP2.

## `HTTP3`

*features* mask bit: CURL_VERSION_HTTP3

HTTP/3 and QUIC support are built-in (Added in 7.66.0)

## `HTTPS-proxy`

*features* mask bit: CURL_VERSION_HTTPS_PROXY

libcurl was built with support for HTTPS-proxy.

## `HTTPSIG`

*features* mask bit: non-existent

libcurl was built with support for RFC 9421 HTTP Message Signatures (Added in
8.22.0)

## `HTTPSRR`

*features* mask bit: non-existent

libcurl was built with EXPERIMENTAL support for HTTPS resource records (Added
in 8.12.0)

## `IDN`

*features* mask bit: CURL_VERSION_IDN

libcurl was built with support for IDNA, domain names with international
letters.

## `IPv6`

*features* mask bit: CURL_VERSION_IPV6

supports IPv6

## `Kerberos`

*features* mask bit: CURL_VERSION_KERBEROS5

supports Kerberos V5 authentication for FTP, IMAP, LDAP, POP3, SMTP and
SOCKSv5 proxy.

## `Largefile`

*features* mask bit: CURL_VERSION_LARGEFILE

libcurl was built with support for large files.

## `libz`

*features* mask bit: CURL_VERSION_LIBZ

supports HTTP deflate using libz

## `MultiSSL`

*features* mask bit: CURL_VERSION_MULTI_SSL

libcurl was built with multiple SSL backends. For details, see
curl_global_sslset(3).

## `NativeCA`

*features* mask bit: non-existent

libcurl was built to enable native CA store, to verify server certificates
(Added in 8.19.0).

## `NTLM`

*features* mask bit: CURL_VERSION_NTLM

supports HTTP NTLM

## `NTLM_WB`

*features* mask bit: CURL_VERSION_NTLM_WB

libcurl was built with support for NTLM delegation to a winbind helper. This
feature was removed from curl in 8.8.0.

## `proxy-HTTP3`

*features* mask bit: non-existent

libcurl was built with EXPERIMENTAL support for HTTP/3 proxy tunneling
(Added in 8.21.0)

## `PSL`

*features* mask bit: CURL_VERSION_PSL

libcurl was built with support for Mozilla's Public Suffix List. This makes
libcurl ignore cookies with a domain that is on the list.

## `SPNEGO`

*features* mask bit: CURL_VERSION_SPNEGO

libcurl was built with support for SPNEGO authentication (Simple and Protected
GSS-API Negotiation Mechanism, defined in RFC 2478.)

## `SSL`

*features* mask bit: CURL_VERSION_SSL

supports SSL (HTTPS/FTPS)

## `SSLS-EXPORT`

*features* mask bit: non-existent

libcurl was built with SSL session import/export support
(experimental, added in 8.12.0)

## `SSPI`

*features* mask bit: CURL_VERSION_SSPI

libcurl was built with support for SSPI. This is only available on Windows and
makes libcurl use Windows-provided functions for Kerberos, NTLM, SPNEGO and
Digest authentication. It also allows libcurl to use the current user
credentials without the app having to pass them on.

## `threadsafe`

*features* mask bit: CURL_VERSION_THREADSAFE

libcurl was built with thread-safety support (Atomic or SRWLOCK) to protect
curl initialization. (Added in 7.84.0) See libcurl-thread(3)

## `TLS-SRP`

*features* mask bit: CURL_VERSION_TLSAUTH_SRP

libcurl was built with support for TLS-SRP (in one or more of the built-in TLS
backends).

## `Unicode`

*features* mask bit: CURL_VERSION_UNICODE

libcurl was built with Unicode support on Windows. This makes non-ASCII
characters work in filenames and options passed to libcurl. (Added in 7.72.0)

## `UnixSockets`

*features* mask bit: CURL_VERSION_UNIX_SOCKETS

libcurl was built with support for Unix domain sockets.

## `zstd`

*features* mask bit: CURL_VERSION_ZSTD

supports HTTP zstd content encoding using zstd library (Added in 7.72.0)

## no name

*features* mask bit: CURL_VERSION_CONV

libcurl was built with support for character conversions provided by
callbacks. Always 0 since 7.82.0. Deprecated.

## no name

*features* mask bit: CURL_VERSION_CURLDEBUG

libcurl was built with memory tracking debug capabilities. This is mainly of
interest for libcurl hackers. Always the same as CURL_VERSION_DEBUG since
8.19.0. Deprecated.

## no name

*features* mask bit: CURL_VERSION_GSSNEGOTIATE

supports HTTP GSS-Negotiate. Deprecated.

## no name

*features* mask bit: CURL_VERSION_KERBEROS4

supports Kerberos V4 (when using FTP). Legacy bit. Deprecated since 7.33.0.

# %PROTOCOLS%

# EXAMPLE

~~~c
int main(void)
{
  curl_version_info_data *ver = curl_version_info(CURLVERSION_NOW);
  printf("libcurl version %u.%u.%u\n",
         (ver->version_num >> 16) & 0xff,
         (ver->version_num >> 8) & 0xff,
         ver->version_num & 0xff);
}
~~~

# %AVAILABILITY%

# RETURN VALUE

A pointer to a curl_version_info_data struct.
