<s>
cURL	B-Protocol
(	O
pronounced	O
like	O
"	O
curl	B-Protocol
"	O
,	O
UK	O
:	O
,	O
US	O
:	O
)	O
is	O
a	O
computer	O
software	O
project	O
providing	O
a	O
library	B-Library
(	O
libcurl	B-Protocol
)	O
and	O
command-line	B-Application
tool	I-Application
(	O
curl	B-Protocol
)	O
for	O
transferring	O
data	O
using	O
various	O
network	O
protocols	O
.	O
</s>
<s>
cURL	B-Protocol
was	O
first	O
released	O
in	O
1996	O
.	O
</s>
<s>
It	O
was	O
originally	O
named	O
httpget	B-Protocol
and	O
then	O
became	O
urlget	B-Protocol
before	O
adopting	O
the	O
current	O
name	O
of	O
cURL	B-Protocol
.	O
</s>
<s>
The	O
original	O
author	O
and	O
lead	O
developer	O
is	O
the	O
Swedish	O
developer	O
Daniel	O
Stenberg	O
,	O
who	O
created	O
cURL	B-Protocol
because	O
he	O
wanted	O
to	O
automate	O
the	O
fetching	O
of	O
currency	O
exchange	O
rates	O
for	O
IRC	O
users	O
.	O
</s>
<s>
libcurl	B-Protocol
is	O
a	O
free	O
client-side	O
URL	O
transfer	O
library	B-Library
,	O
supporting	O
cookies	B-Application
,	O
DICT	B-Library
,	O
FTP	B-Protocol
,	O
FTPS	B-Protocol
,	O
Gopher	B-Protocol
,	O
HTTP/1	B-Protocol
(	O
with	O
HTTP/2	B-Protocol
and	O
HTTP/3	B-Protocol
support	O
)	O
,	O
HTTP	B-Protocol
POST	I-Protocol
,	O
HTTP	B-Protocol
PUT	O
,	O
HTTP	B-Protocol
proxy	O
tunneling	O
,	O
HTTPS	B-Protocol
,	O
IMAP	B-Protocol
,	O
Kerberos	B-Protocol
,	O
LDAP	B-Protocol
,	O
MQTT	B-Application
,	O
POP3	B-Protocol
,	O
RTSP	B-Protocol
,	O
RTMP	B-Operating_System
,	O
SCP	B-Protocol
,	O
SMTP	B-Protocol
,	O
and	O
SMB	B-Operating_System
.	O
</s>
<s>
The	O
library	B-Library
supports	O
the	O
file	O
URI	O
scheme	O
,	O
SFTP	B-Protocol
,	O
Telnet	B-Protocol
,	O
TFTP	B-Device
,	O
file	O
transfer	O
resume	O
,	O
FTP	B-Protocol
uploading	O
,	O
HTTP	B-Protocol
form-based	O
upload	O
,	O
HTTPS	B-Protocol
certificates	O
,	O
LDAPS	B-Protocol
,	O
proxies	O
,	O
and	O
user-plus-password	O
authentication	O
.	O
</s>
<s>
The	O
libcurl	B-Protocol
library	B-Library
is	O
portable	O
.	O
</s>
<s>
It	O
builds	O
and	O
works	O
identically	O
on	O
many	O
platforms	O
,	O
including	O
AIX	B-Application
,	O
AmigaOS	B-Application
,	O
Android	B-Application
,	O
BeOS	B-Application
,	O
BlackBerry	B-Application
Tablet	I-Application
OS	I-Application
and	O
BlackBerry	B-Application
10	I-Application
,	O
OpenVMS	B-Operating_System
,	O
Darwin	B-Operating_System
,	O
DOS	B-Device
,	O
FreeBSD	B-Operating_System
,	O
HP-UX	B-Application
,	O
HURD	B-Application
,	O
iOS	B-Application
,	O
IRIX	B-Operating_System
,	O
Linux	B-Application
,	O
macOS	B-Application
,	O
NetBSD	B-Device
,	O
NetWare	B-Operating_System
,	O
OpenBSD	B-Operating_System
,	O
OS/2	B-Application
,	O
QNX	B-Operating_System
Neutrino	I-Operating_System
,	O
RISC	B-Operating_System
OS	I-Operating_System
,	O
Solaris	B-Application
,	O
Symbian	B-Operating_System
,	O
Tru64	B-Operating_System
,	O
Ultrix	B-Operating_System
,	O
UnixWare	B-Operating_System
,	O
and	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
The	O
libcurl	B-Protocol
library	B-Library
is	O
free	O
,	O
thread-safe	B-Operating_System
and	O
IPv6	B-Protocol
compatible	O
.	O
</s>
<s>
Bindings	B-Application
are	O
available	O
for	O
more	O
than	O
50	O
languages	B-Language
,	O
including	O
C/C	O
++	O
,	O
Java	B-Language
,	O
Julia	B-Application
(	O
is	O
bundled	O
with	O
)	O
,	O
PHP	B-Application
and	O
Python	B-Language
.	O
</s>
<s>
The	O
libcurl	B-Protocol
library	B-Library
supports	O
GnuTLS	B-Application
,	O
mbed	B-Language
TLS	I-Language
,	O
NSS	B-Protocol
,	O
gskit	O
on	O
IBM	B-Application
i	I-Application
,	O
SChannel	B-Protocol
on	O
Windows	O
,	O
Secure	O
Transport	O
on	O
macOS	B-Application
and	O
iOS	B-Application
,	O
SSL/TLS	B-Protocol
through	O
OpenSSL	B-Language
,	O
BoringSSL	B-Protocol
,	O
libreSSL	B-Language
,	O
AmiSSL	O
,	O
wolfSSL	B-Protocol
,	O
BearSSL	O
and	O
rustls	O
.	O
</s>
<s>
curl	B-Protocol
is	O
a	O
command-line	B-Application
tool	I-Application
for	O
getting	O
or	O
sending	O
data	O
including	O
files	O
using	O
URL	O
syntax	O
.	O
</s>
<s>
Since	O
curl	B-Protocol
uses	O
libcurl	B-Protocol
,	O
it	O
supports	O
every	O
protocol	O
libcurl	B-Protocol
supports	O
.	O
</s>
<s>
curl	B-Protocol
supports	O
HTTPS	B-Protocol
and	O
performs	O
SSL	O
certificate	O
verification	O
by	O
default	O
when	O
a	O
secure	O
protocol	O
is	O
specified	O
such	O
as	O
HTTPS	B-Protocol
.	O
</s>
<s>
When	O
curl	B-Protocol
connects	O
to	O
a	O
remote	O
server	O
via	O
HTTPS	B-Protocol
,	O
it	O
will	O
obtain	O
the	O
remote	O
server	O
certificate	O
,	O
then	O
check	O
against	O
its	O
CA	B-Architecture
certificate	I-Architecture
store	O
the	O
validity	O
of	O
the	O
remote	O
server	O
to	O
ensure	O
the	O
remote	O
server	O
is	O
the	O
one	O
it	O
claims	O
to	O
be	O
.	O
</s>
<s>
Some	O
curl	B-Protocol
packages	O
are	O
bundled	O
with	O
CA	B-Architecture
certificate	I-Architecture
store	O
file	O
.	O
</s>
<s>
There	O
are	O
several	O
options	O
to	O
specify	O
a	O
CA	B-Architecture
certificate	I-Architecture
such	O
as	O
and	O
.	O
</s>
<s>
The	O
option	O
can	O
be	O
used	O
to	O
specify	O
the	O
location	O
of	O
the	O
CA	B-Architecture
certificate	I-Architecture
store	O
file	O
.	O
</s>
<s>
In	O
the	O
Windows	O
platform	O
,	O
if	O
a	O
CA	B-Architecture
certificate	I-Architecture
file	O
is	O
not	O
specified	O
,	O
curl	B-Protocol
will	O
look	O
for	O
a	O
CA	B-Architecture
certificate	I-Architecture
file	O
name	O
“	O
curl-ca-bundle.crt	O
”	O
in	O
the	O
following	O
order	O
:	O
</s>
<s>
Directory	O
where	O
the	O
curl	B-Protocol
program	O
is	O
located	O
.	O
</s>
<s>
curl	B-Protocol
will	O
return	O
an	O
error	O
message	O
if	O
the	O
remote	O
server	O
is	O
using	O
a	O
self-signed	O
certificate	O
,	O
or	O
if	O
the	O
remote	O
server	O
certificate	O
is	O
not	O
signed	O
by	O
a	O
CA	O
listed	O
in	O
the	O
CA	O
cert	O
file	O
.	O
</s>
<s>
Alternatively	O
,	O
if	O
the	O
remote	O
server	O
is	O
trusted	O
,	O
the	O
remote	O
server	O
CA	B-Architecture
certificate	I-Architecture
can	O
be	O
added	O
to	O
the	O
CA	B-Architecture
certificate	I-Architecture
store	O
file	O
.	O
</s>
<s>
Basic	O
use	O
of	O
curl	B-Protocol
involves	O
simply	O
typing	O
at	O
the	O
command	B-Application
line	I-Application
,	O
followed	O
by	O
the	O
URL	O
of	O
the	O
output	O
to	O
retrieve	O
:	O
</s>
<s>
curl	B-Protocol
defaults	O
to	O
displaying	O
the	O
output	O
it	O
retrieves	O
to	O
the	O
standard	O
output	O
specified	O
on	O
the	O
system	O
(	O
usually	O
the	O
terminal	O
window	O
)	O
.	O
</s>
