Predefined Constants

Enables the use of an abstract Unix domain socket instead of establishing a TCP connection to a host and sets the path to the given string. This option shares the same semantics as CURLOPT_UNIX_SOCKET_PATH. These two options share the same storage and therefore only one of them can be set per handle. Available as of PHP 7.3.0 and cURL 7.53.0.

Sets a string with the contents of the Accept-Encoding: header sent in an HTTP request. Set to null to disable sending the Accept-Encoding: header. Defaults to null. Available as of cURL 7.21.6.

The maximum number of milliseconds to wait for a server to connect back to cURL when an active FTP connection is used. This option accepts any value that can be cast to a valid int. Defaults to 60000 milliseconds. Available as of cURL 7.24.0.

The scope id value to use when connecting to IPv6 addresses. This option accepts any value that can be cast to a valid int. Defaults to 0. Available as of cURL 7.19.0.

Pass a string with the filename for cURL to use as the Alt-Svc cache file to read existing cache contents from and possibly also write it back to a after a transfer, unless CURLALTSVC_READONLYFILE is set via CURLOPT_ALTSVC_CTRL. Available as of PHP 8.2.0 and cURL 7.64.1.

Populate the bitmask with the correct set of features to instruct cURL how to handle Alt-Svc for the transfers using this handle. cURL only accepts Alt-Svc headers over HTTPS. It will also only complete a request to an alternative origin if that origin is properly hosted over HTTPS. Setting any bit will enable the alt-svc engine. Set to any of the CURLALTSVC_* constants. Defaults to Alt-Svc handling being disabled. Available as of PHP 8.2.0 and cURL 7.64.1.

Setting this option to 1 will cause FTP uploads to append to the remote file instead of overwriting it. Defaults to 0. Available as of cURL 7.17.0.

true to automatically set the Referer: field in requests where it follows a Location: redirect. Defaults to 0. Available as of cURL 7.1.0.

Provides AWS V4 signature authentication on HTTP(S) header as a string. This option overrides any other authentication types that have been set in CURLOPT_HTTPAUTH. This method cannot be combined with other authentication types. Available as of PHP 8.2.0 and cURL 7.75.0.

This constant is no longer used as of PHP 5.5.0. Deprecated as of PHP 8.4.0.

The size of the buffer to use for each read. There is no guarantee this request will be fulfilled, however. This option accepts any value that can be cast to a valid int. Defaults to CURL_MAX_WRITE_SIZE (currently, 16kB). Available as of cURL 7.10.

A string with the name of a file holding one or more certificates to verify the peer with. This only makes sense when used in combination with CURLOPT_SSL_VERIFYPEER. Might require an absolute path. Available as of cURL 7.4.2.

A string with the name of a PEM file holding one or more certificates to verify the peer with. This option overrides CURLOPT_CAINFO. Available as of PHP 8.2.0 and cURL 7.77.0.

A string with a directory that holds multiple CA certificates. Use this option alongside CURLOPT_SSL_VERIFYPEER. Available as of cURL 7.9.8.

Sets the maximum time in seconds any in memory cached CA certificate store may be kept and reused for new connections. This option accepts any value that can be cast to a valid int. Defaults to 86400 (24 hours). Available as of PHP 8.3.0 and cURL 7.87.0

true to output SSL certification information to STDERR on secure transfers. Requires CURLOPT_VERBOSE to be on to have an effect. Defaults to false. Available as of cURL 7.19.1.

The number of seconds to wait while trying to connect. Use 0 to wait indefinitely. This option accepts any value that can be cast to a valid int. Defaults to 300. Available as of cURL 7.7.0.

The number of milliseconds to wait while trying to connect. Use 0 to wait indefinitely. If cURL is built to use the standard system name resolver, that portion of the connect will still use full-second resolution for timeouts with a minimum timeout allowed of one second. This option accepts any value that can be cast to a valid int. Defaults to 300000. Available as of cURL 7.16.2.

true tells the library to perform all the required proxy authentication and connection setup, but no data transfer. This option is implemented for HTTP, SMTP and POP3. Defaults to false. Available as of cURL 7.15.2.

Connect to a specific host and port instead of the URL's host and port. Accepts an array of strings with the format HOST:PORT:CONNECT-TO-HOST:CONNECT-TO-PORT. Available as of PHP 7.0.7 and cURL 7.49.0.

A string with the contents of the Cookie: header to be used in the HTTP request. Note that multiple cookies are separated with a semicolon followed by a space (e.g., fruit=apple; colour=red). Available as of cURL 7.1.0.

A string with the name of the file containing the cookie data. The cookie file can be in Netscape format, or just plain HTTP-style headers dumped into a file. If the name is an empty string, no cookies are loaded, but cookie handling is still enabled. Available as of cURL 7.1.0.

A string with the name of a file to save all internal cookies to when the handle's destructor is called. Available as of cURL 7.9.0.

A cookie string (i.e. a single line in Netscape/Mozilla format, or a regular HTTP-style Set-Cookie header) adds that single cookie to the internal cookie store. ALL erases all cookies held in memory , SESS erases all session cookies held in memory , FLUSH writes all known cookies to the file specified by CURLOPT_COOKIEJAR , RELOAD loads all cookies from the files specified by CURLOPT_COOKIEFILE . Available as of cURL 7.14.1.

true to mark this as a new cookie "session". It will force cURL to ignore all cookies it is about to load that are "session cookies" from the previous session. By default, cURL always stores and loads all cookies, independent if they are session cookies or not. Session cookies are cookies without expiry date and they are meant to be alive and existing for this "session" only. Available as of cURL 7.9.7.

true to convert Unix newlines to CRLF newlines on transfers. Available as of cURL 7.1.0.

Pass a string naming a file with the concatenation of CRL (Certificate Revocation List) (in PEM format) to use in the certificate validation that occurs during the SSL exchange. When cURL is built to use GnuTLS, there is no way to influence the use of CRL passed to help in the verification process. When cURL is built with OpenSSL support, X509_V_FLAG_CRL_CHECK and X509_V_FLAG_CRL_CHECK_ALL are both set, requiring CRL check against all the elements of the certificate chain if a CRL file is passed. Also note that CURLOPT_CRLFILE implies CURLSSLOPT_NO_PARTIALCHAIN as of cURL 7.71.0 due to an OpenSSL bug. Available as of cURL 7.19.0.

A custom request method to use instead of GET or HEAD when doing a HTTP request. This is useful for doing DELETE or other, more obscure HTTP requests. Valid values are things like GET, POST, CONNECT and so on; i.e. Do not enter a whole HTTP request line here. For instance, entering GET /index.html HTTP/1.0\r\n\r\n would be incorrect. This option accepts a string or null. Available as of cURL 7.1.0.

Note:

Don't do this without making sure the server supports the custom request method first.

A string with the default protocol to use if the URL is missing a scheme name. Available as of PHP 7.0.7 and cURL 7.45.0.

Setting this option to 1 will have different effects based on the protocol it is used with. FTP and SFTP based URLs will list only the names of files in a directory. POP3 will list the email message or messages on the POP3 server. For FILE, this option has no effect as directories are always listed in this mode. Using this option with CURLOPT_WILDCARDMATCH will prevent the latter from having any effect. Defaults to 0. Available as of cURL 7.17.0.

true to not allow URLs that include a username. Usernames are allowed by default. Available as of PHP 7.3.0 and cURL 7.61.0.

The number of seconds to keep DNS entries in memory. This option is set to 120 (2 minutes) by default. This option accepts any value that can be cast to a valid int. Available as of cURL 7.9.3.

Set the name of the network interface that the DNS resolver should bind to. This must be an interface name (not an address). This option accepts a string or null. Available as of PHP 7.0.7 and cURL 7.33.0

Set the local IPv4 address that the resolver should bind to. The argument should contain a single numerical IPv4 address. This option accepts a string or null. Available as of PHP 7.0.7 and cURL 7.33.0.

Set the local IPv6 address that the resolver should bind to. The argument should contain a single numerical IPv6 address. This option accepts a string or null. Available as of PHP 7.0.7 and cURL 7.33.0.

Pass a string with a comma-separated list of DNS servers to be used instead of the system default (e.g.: 192.168.1.100,192.168.1.101:8080). Available as of cURL 7.24.0.

true to shuffle the order of all returned addresses so that they will be used in a random order, when a name is resolved and more than one IP address is returned. This may cause IPv4 to be used before IPv6 or vice versa. Available as of PHP 7.3.0 and cURL 7.60.0.

true to use a global DNS cache. This option is not thread-safe. It is conditionally enabled by default if PHP is built for non-threaded use (CLI, FCGI, Apache2-Prefork, etc.). Available as of cURL 7.9.3 and deprecated as of cURL 7.11.1. As of PHP 8.4, this option no longer has any effect.

Set to 2 to verify the DNS-over-HTTPS server's SSL certificate name fields against the host name. Available as of PHP 8.2.0 and cURL 7.76.0.

Set to 1 to enable and 0 to disable verification of the authenticity of the DNS-over-HTTPS server's SSL certificate. Available as of PHP 8.2.0 and cURL 7.76.0.

Set to 1 to enable and 0 to disable the verification of the status of the DNS-over-HTTPS server certificate using the "Certificate Status Request" TLS extension (OCSP stapling). Available as of PHP 8.2.0 and cURL 7.76.0.

Provides the DNS-over-HTTPS URL. This option accepts a string or null. Available as of PHP 8.1.0 and cURL 7.62.0.

Like CURLOPT_RANDOM_FILE, except a filename to an Entropy Gathering Daemon socket. Available as of cURL 7.7.0 and deprecated as of cURL 7.84.0.

The contents of the Accept-Encoding: header as a string. This enables decoding of the response. Supported encodings are: identity, deflate, gzip. If an empty string is set, a header containing all supported encoding types is sent. Available as of cURL 7.10 and deprecated as of cURL 7.21.6.

The timeout for Expect: 100-continue responses in milliseconds. Defaults to 1000 milliseconds. This option accepts any value that can be cast to a valid int. Available as of PHP 7.0.7 and cURL 7.36.0.

true to fail verbosely if the HTTP code returned is greater than or equal to 400. The default behavior is to return the page normally, ignoring the code. Available as of cURL 7.1.0.

Accepts a file handle resource to the file that the transfer should be written to. The default is STDOUT (the browser window). Available as of cURL 7.1.0 and deprecated as of cURL 7.9.7.

Set to true to attempt to retrieve the modification date of the remote document. This value can be retrieved using the CURLINFO_FILETIME option with curl_getinfo(). Available as of cURL 7.5.0.

Pass a callable that will be used for wildcard matching. The signature of the callback should be:

curlHandle

The cURL handle.

pattern

The wildcard pattern.

string

The string to run the wildcard pattern matching on.

Set to true to follow any Location: header that the server sends as part of the HTTP header. See also CURLOPT_MAXREDIRS. This constant is not available when open_basedir is enabled. Available as of cURL 7.1.0.

Set to true to force the connection to explicitly close when it has finished processing, and not be pooled for reuse. Available as of cURL 7.7.0.

Set to true to force the use of a new connection instead of a cached one. Available as of cURL 7.7.0.

Set to true to append to the remote file instead of overwriting it. Available as of cURL 7.1.0 and deprecated as of cURL 7.16.4.

An alias of CURLOPT_TRANSFERTEXT. Use that instead. Available as of cURL 7.1, deprecated as of cURL 7.11.1 and last available in cURL 7.15.5. Removed as of PHP 7.3.0.

Set to true to only list the names of an FTP directory. Available as of cURL 7.1.0 and deprecated as of cURL 7.16.4.

A string which will be used to get the IP address to use for the FTP PORT instruction. The PORT instruction tells the remote server to connect to our specified IP address. The string may be a plain IP address, a hostname, a network interface name (under Unix), or just a plain - to use the system's default IP address. This option accepts a string or null. Available as of cURL 7.1.0.

Set the FTP over SSL authentication method (if activated) to any of the CURLFTPAUTH_* constants. Defaults to CURLFTPAUTH_DEFAULT. Available as of cURL 7.12.2.

Pass a string that will be sent as account information over FTP (using the ACCT command) after username and password has been provided to the server. Set to null to disable sending the account information. Defaults to null. Available as of cURL 7.13.0.

Pass a string that will be used to try to authenticate over FTP if the USER/PASS negotiation fails. Available as of cURL 7.15.5.

Set to true to create missing directories when an FTP operation encounters a path that currently doesn't exist. Available as of cURL 7.10.7.

Tell cURL which method to use to reach a file on a FTP(S) server. Possible values are any of the CURLFTPMETHOD_* constants. Defaults to CURLFTPMETHOD_MULTICWD. Available as of cURL 7.15.1.

A timeout in seconds cURL will wait for a response from an FTP server. This option overrides CURLOPT_TIMEOUT. This option accepts any value that can be cast to a valid int. This option name is replaced with CURLOPT_SERVER_RESPONSE_TIMEOUT, available as of PHP 8.4.0. Available as of cURL 7.10.8 and deprecated as of cURL 7.85.0.

If this option is set to 1 cURL will not use the IP address the server suggests in its 227-response to cURL's PASV command but will use the IP address it used for the connection. The port number received from the 227-response will not be ignored by cURL. Defaults to 1 as of cURL 7.74.0 and 0 prior to that. Available as of cURL 7.15.0.

Available as of cURL 7.11.0 and deprecated as of cURL 7.16.4.

This option makes cURL use CCC (Clear Command Channel) which shuts down the SSL/TLS layer after authenticating making the rest of the control channel communication unencrypted. Use one of the CURLFTPSSL_CCC_* constants. Defaults to CURLFTPSSL_CCC_NONE. Available as of cURL 7.16.1.

Set to true to use EPRT (and LPRT) when doing active FTP downloads. Set to false to disable EPRT and LPRT and use PORT only. Available as of cURL 7.10.5.

Set to true to first try an EPSV command for FTP transfers before reverting back to PASV. Set to false to disable EPSV. Available as of cURL 7.9.2.

Set to 1 to send a PRET command before PASV (and EPSV). Has no effect when using the active FTP transfers mode. Defaults to 0. Available as of cURL 7.20.0.

Set to CURLGSSAPI_DELEGATION_FLAG to allow unconditional GSSAPI credential delegation. Set to CURLGSSAPI_DELEGATION_POLICY_FLAG to delegate only if the OK-AS-DELEGATE flag is set in the service ticket. Defaults to CURLGSSAPI_DELEGATION_NONE. Available as of cURL 7.22.0.

Head start for IPv6 for the happy eyeballs algorithm. Happy eyeballs attempts to connect to both IPv4 and IPv6 addresses for dual-stack hosts, preferring IPv6 first for timeout milliseconds. Defaults to CURL_HET_DEFAULT, which is currently 200 milliseconds. This option accepts any value that can be cast to a valid int. Available as of PHP 7.3.0 and cURL 7.59.0

true to send an HAProxy PROXY protocol v1 header at the start of the connection. The default action is not to send this header. Available as of PHP 7.3.0 and cURL 7.60.0.

Set to true to include the headers in the output sent to the callback defined by CURLOPT_WRITEFUNCTION. Available as of cURL 7.1.0.

A callable with the following signature:

curlHandle

The cURL handle.

headerData

The header data which must be written by the callback.

Send HTTP headers to both proxy and host or separately. Possible values are any of the CURLHEADER_* constants. Defaults to CURLHEADER_SEPARATE as of cURL 7.42.1, and CURLHEADER_UNIFIED prior to that. Available as of PHP 7.0.7 and cURL 7.37.0.

string with HSTS (HTTP Strict Transport Security) cache file name or null to allow HSTS without reading from or writing to any file and clear the list of files to read HSTS data from. Available as of PHP 8.2.0 and cURL 7.74.0.

Accepts a bitmask of HSTS (HTTP Strict Transport Security) features defined by the CURLHSTS_* constants. Available as of PHP 8.2.0 and cURL 7.74.0.

Whether to allow HTTP/0.9 responses. Defaults to false as of cURL 7.66.0; formerly it defaulted to true. Available as of PHP 7.3.15 and 7.4.3, respectively, and cURL 7.64.0.

An array of HTTP 200 responses that will be treated as valid responses and not as errors. Available as of cURL 7.10.3.

A bitmask of HTTP authentication method(s) to use. The options are: CURLAUTH_BASIC, CURLAUTH_DIGEST, CURLAUTH_GSSNEGOTIATE, CURLAUTH_NTLM, CURLAUTH_AWS_SIGV4, CURLAUTH_ANY, CURLAUTH_ANYSAFE. If more than one method is used, cURL will poll the server to see what methods it supports and pick the best one. CURLAUTH_ANY sets all bits. cURL will automatically select the one it finds most secure. CURLAUTH_ANYSAFE sets all bits except CURLAUTH_BASIC. cURL will automatically select the one it finds most secure. Available as of cURL 7.10.6.

Set to true to reset the HTTP request method to GET. Since GET is the default, this is only necessary if the request method has been changed. Available as of cURL 7.8.1.

An array of HTTP header fields to set, in the format array('Content-type: text/plain', 'Content-length: 100') Available as of cURL 7.1.0.

true to tunnel through a given HTTP proxy. Available as of cURL 7.3.0.

false to get the raw HTTP response body. Available as of cURL 7.16.2.

If set to 0, transfer decoding is disabled. If set to 1, transfer decoding is enabled. cURL does chunked transfer decoding by default unless this option is set to 0. Defaults to 1. Available as of cURL 7.16.2.

Set to one of the CURL_HTTP_VERSION_* constants for cURL to use the specified HTTP version. Available as of cURL 7.9.1.

If set to 1, ignore the Content-Length header in the HTTP response and ignore asking for or relying on it for FTP transfers. Defaults to 0. Available as of cURL 7.14.1.

Accepts a file handle resource to the file that the transfer should be read from when uploading. Available as of cURL 7.1.0 and deprecated as of cURL 7.9.7. Use CURLOPT_READDATA instead.

The expected size, in bytes, of the file when uploading a file to a remote site. Note that using this option will not stop cURL from sending more data, as exactly what is sent depends on CURLOPT_READFUNCTION. This option accepts any value that can be cast to a valid int. Available as of cURL 7.1.0.

Set to a string with the name of the outgoing network interface to use. This can be an interface name, an IP address or a host name. Available as of cURL 7.1.0.

Allows an application to select what kind of IP addresses to use when resolving host names. This is only interesting when using host names that resolve addresses using more than one version of IP. Set to one of the CURL_IPRESOLVE_* constants. Defaults to CURL_IPRESOLVE_WHATEVER. Available as of cURL 7.10.8.

If set to a string naming a file holding a CA certificate in PEM format, an additional check against the peer certificate is performed to verify the issuer is indeed the one associated with the certificate provided by the option. For the result of the check to be considered a failure, this option should be used in combination with the CURLOPT_SSL_VERIFYPEER option. Available as of cURL 7.19.0.

Pass a string with binary data of a CA SSL certificate in PEM format. If set, an additional check against the peer certificate is performed to verify the issuer is the one associated with the certificate provided by the option. Available as of PHP 8.1.0 and cURL 7.71.0.

Set to true to keep sending the request body if the HTTP code returned is equal to or larger than 300. The default action would be to stop sending and close the stream or connection. Suitable for manual NTLM authentication. Most applications do not need this option. Available as of PHP 7.3.0 and cURL 7.51.0.

Set to a string with the password required to use the CURLOPT_SSLKEY or CURLOPT_SSH_PRIVATE_KEYFILE private key. Setting this option to null disables using a password for these options. Available as of cURL 7.17.0.

The KRB4 (Kerberos 4) security level. Any of the following string values (in order from least to most powerful) are valid: clear, safe, confidential, private. If the string does not match one of these, private is used. Setting this option to null will disable KRB4 security. Currently KRB4 security only works with FTP transactions. Available as of cURL 7.3.0 and deprecated as of cURL 7.17.0.

Set the kerberos security level for FTP and also enables kerberos awareness. This should be set to one of the following strings: clear, safe, confidential, private. If the string is set but does not match one of these, private is used. Setting this option to null will disable kerberos support for FTP. Defaults to null. Available as of cURL 7.16.4.

Sets the local port number of the socket used for the connection. This option accepts any value that can be cast to a valid int. Defaults to 0. Available as of cURL 7.15.2.

The number of attempts cURL makes to find a working local port number, starting with the one set with CURLOPT_LOCALPORT. This option accepts any value that can be cast to a valid int. Defaults to 1. Available as of cURL 7.15.2.

Can be used to set protocol specific login options, such as the preferred authentication mechanism via AUTH=NTLM or AUTH=*, and should be used in conjunction with the CURLOPT_USERNAME option. Available as of PHP 7.0.7 and cURL 7.34.0.

The transfer speed, in bytes per second, that the transfer should be below during the count of CURLOPT_LOW_SPEED_TIME seconds before PHP considers the transfer too slow and aborts. This option accepts any value that can be cast to a valid int. Available as of cURL 7.1.0.

The number of seconds the transfer speed should be below CURLOPT_LOW_SPEED_LIMIT before PHP considers the transfer too slow and aborts. This option accepts any value that can be cast to a valid int. Available as of cURL 7.1.0.

Set a string with the authentication address (identity) of a submitted message that is being relayed to another server. The address should not be specified within a pair of angled brackets (><). If an empty string is used then a pair of brackets are sent by cURL as required by RFC 2554. Available as of cURL 7.25.0.

Set a string with the sender's email address when sending SMTP mail. The email address should be specified with angled brackets (><) around it, which if not specified are added automatically. If this parameter is not specified then an empty address is sent to the SMTP server which might cause the email to be rejected. Available as of cURL 7.20.0.

Set to an array of strings with the recipients to pass to the server in an SMTP mail request. Each recipient should be specified within a pair of angled brackets (><). If an angled bracket is not used as the first character, cURL assumes a single email address has been provided and encloses that address within brackets. Available as of cURL 7.20.0.

Set to 1 to allow RCPT TO command to fail for some recipients which makes cURL ignore errors for individual recipients and proceed with the remaining accepted recipients. If all recipients trigger failures and this flag is specified, cURL aborts the SMTP conversation and returns the error received from to the last RCPT TO command. Replaced by CURLOPT_MAIL_RCPT_ALLOWFAILS as of cURL 8.2.0. Available as of PHP 8.2.0 and cURL 7.69.0. Deprecated as of cURL 8.2.0.

The maximum idle time allowed for an existing connection to be considered for reuse. Default maximum age is set to 118 seconds. This option accepts any value that can be cast to a valid int. Available as of PHP 8.2.0 and cURL 7.65.0.

The maximum amount of persistent connections that are allowed. When the limit is reached, the oldest one in the cache is closed to prevent increasing the number of open connections. This option accepts any value that can be cast to a valid int. Available as of cURL 7.7.0.

Sets the maximum accepted size (in bytes) of a file to download. If the file requested is found larger than this value, the transfer is aborted and CURLE_FILESIZE_EXCEEDED is returned. Passing 0 disables this option, and passing a negative size returns a CURLE_BAD_FUNCTION_ARGUMENT. If the file size is not known prior to the start of download, this option has no effect. For setting a size limit above 2GB, CURLOPT_MAXFILESIZE_LARGE should be used. As of cURL 8.4.0, this option also stops ongoing transfers if they reach this threshold. This option accepts any value that can be cast to a valid int. Defaults to 0. Available as of cURL 7.10.8.

The maximum file size in bytes allowed to download. If the file requested is found larger than this value, the transfer will not start and CURLE_FILESIZE_EXCEEDED will be returned. The file size is not always known prior to download, and for such files this option has no effect even if the file transfer ends up being larger than this given limit. This option accepts any value that can be cast to a valid int. Available as of PHP 8.2.0 and cURL 7.11.0.

The maximum time in seconds, since the creation of the connection, that is allowed for an existing connection to have for it to be considered for reuse. If a connection is found in the cache that is older than this value, it will instead be closed once any in-progress transfers are complete. Default is 0 seconds, meaning the option is disabled and all connections are eligible for reuse. This option accepts any value that can be cast to a valid int. Available as of PHP 8.2.0 and cURL 7.80.0.

The maximum amount of HTTP redirections to follow. Use this option alongside CURLOPT_FOLLOWLOCATION. Default value of 20 is set to prevent infinite redirects. Setting to -1 allows inifinite redirects, and 0 refuses all redirects. Available as of cURL 7.5.0.

If a download exceeds this speed (counted in bytes per second) on cumulative average during the transfer, the transfer will pause to keep the average rate less than or equal to the parameter value. Defaults to unlimited speed. This option accepts any value that can be cast to a valid int. Available as of cURL 7.15.5.

If an upload exceeds this speed (counted in bytes per second) on cumulative average during the transfer, the transfer will pause to keep the average rate less than or equal to the parameter value. Defaults to unlimited speed. This option accepts any value that can be cast to a valid int. Available as of cURL 7.15.5.

Set to a bitmask of CURLMIMEOPT_* constants. Currently there is only one available option: CURLMIMEOPT_FORMESCAPE. Available as of PHP 8.3.0 and cURL 7.81.0.

Set to true to be completely silent with regards to the cURL functions. Use CURLOPT_RETURNTRANSFER instead. Available as of cURL 7.1.0, deprecated as of cURL 7.8.0 and last available in cURL 7.15.5. Removed as of PHP 7.3.0.

Set to true to scan the ~/.netrc file to find a username and password for the remote site that a connection is being established with. Available as of cURL 7.1.0.

Set a string containing the full path name to a .netrc file. If this option is omitted and CURLOPT_NETRC is set, cURL checks for a .netrc file in the current user's home directory. Available as of cURL 7.11.0.

Sets the value of the permissions (int) that is set on newly created directories on the remote server. The default value is 0755. The only protocols that can use this are sftp://, scp:// and file://. Available as of cURL 7.16.4.

Sets the value of the permissions (as an int) that are set on newly created files on the remote server. The default value is 0644. The only protocols that can use this are sftp://, scp:// and file://. Available as of cURL 7.16.4.

Set to true to exclude the body from the output. For HTTP(S), cURL makes a HEAD request. For most other protocols, cURL is not asking for the body data at all. Changing this to false will result in body data being included in the output. Available as of cURL 7.1.0.

Set to true to disable the progress meter for cURL transfers.

Note:

PHP automatically sets this option to true, this should only be changed for debugging purposes.

Set a string consisting of a comma separated list of hostnames that do not require a proxy to get reached. Each name in this list is matched as either a domain which contains the hostname or the hostname itself. The only wildcard available in the string is a single * character which matches all hosts, effectively disabling the proxy. Setting this option to an empty string enables the proxy for all hostnames. Since cURL 7.86.0, IP addresses set with this option can be provided using CIDR notation. Available as of cURL 7.19.4.

true to ignore any cURL function that causes a signal to be sent to the PHP process. This is turned on by default in multi-threaded SAPIs so timeout options can still be used. Available as of cURL 7.10.

A callable with the following signature:

curlHandle

The cURL handle.

passwordPrompt

A password prompt.

maximumPasswordLength

The maximum length of the password.

Set to a string with the password to use in authentication. Available as of cURL 7.19.1.

Set to true for cURL not alter URL paths before passing them on to the server. Defaults to false, which squashes sequences of /../ or /./ that may exist in the URL's path part which is supposed to be removed according to RFC 3986 section 5.2.4. Available as of PHP 7.0.7 and cURL 7.42.0.

Set a string with the pinned public key. The string can be the file name of the pinned public key in a PEM or DER file format. The string can also be any number of base64 encoded sha256 hashes preceded by sha256// and separated by ;. Available as of PHP 7.0.7 and cURL 7.39.0.

Set to true to wait for an existing connection to confirm whether it can do multiplexing and use it if it can before creating and using a new connection. Available as of PHP 7.0.7 and cURL 7.43.0.

An int with an alternative port number to connect to instead of the one specified in the URL or the default port for the used protocol. Available as of cURL 7.1.0.

Set to true to do a HTTP POST request. This request uses the application/x-www-form-urlencoded header. Defaults to false. Available as of cURL 7.1.0.

The full data to post in a HTTP POST operation. This parameter can either be passed as a urlencoded string like 'para1=val1&para2=val2&...' or as an array with the field name as key and field data as value. If value is an array, the Content-Type header will be set to multipart/form-data. Files can be sent using CURLFile or CURLStringFile, in which case value must be an array. Available as of cURL 7.1.0.

An array of FTP command strings to execute on the server after the FTP request has been performed. Available as of cURL 7.1.0.

Set to a bitmask of CURL_REDIR_POST_301, CURL_REDIR_POST_302 and CURL_REDIR_POST_303 if the HTTP POST method should be maintained when CURLOPT_FOLLOWLOCATION is set and a specific type of redirect occurs. Available as of cURL 7.19.1.

Set a string holding the host name or dotted numerical IP address to be used as the preproxy that cURL connects to before it connects to the HTTP(S) proxy specified in the CURLOPT_PROXY option for the upcoming request. The preproxy can only be a SOCKS proxy and it should be prefixed with [scheme]:// to specify which kind of socks is used. A numerical IPv6 address must be written within [brackets]. Setting the preproxy to an empty string explicitly disables the use of a preproxy. To specify port number in this string, append :[port] to the end of the host name. The proxy's port number may optionally be specified with the separate option CURLOPT_PROXYPORT. Defaults to using port 1080 for proxies if a port is not specified. Available as of PHP 7.3.0 and cURL 7.52.0.

Set an array of FTP command strings to pass to the server after the transfer type is set. These commands are not performed when a directory listing is performed, only for file transfers. Available as of cURL 7.9.5.

Any data that should be associated with this cURL handle. This data can subsequently be retrieved with the CURLINFO_PRIVATE option of curl_getinfo(). cURL does nothing with this data. When using a cURL multi handle, this private data is typically a unique key to identify a standard cURL handle. Available as of cURL 7.10.3.

A callable with the following signature:

curlHandle

The cURL handle.

bytesToDownload

The total number of bytes expected to be downloaded in this transfer.

bytesDownloaded

The number of bytes downloaded so far.

bytesToUpload

The total number of bytes expected to be uploaded in this transfer.

bytesUploaded

The number of bytes uploaded so far.

Note:

The callback is only called when the CURLOPT_NOPROGRESS option is set to false.

Bitmask of CURLPROTO_* values. If used, this bitmask limits what protocols cURL may use in the transfer. Defaults to CURLPROTO_ALL, ie. cURL will accept all protocols it supports. See also CURLOPT_REDIR_PROTOCOLS. Available as of cURL 7.19.4 and deprecated as of cURL 7.85.0.

Set to a string with a comma separated list of case insensitive protocol names (URL schemes) to allow in the transfer. Set to ALL to enable all protocols. By default, cURL accepts all protocols it was built with support for. Available protocols are: DICT, FILE, FTP, FTPS, GOPHER, GOPHERS, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S, RTMP, RTMPE, RTMPS, RTMPT, RTMPTE, RTMPTS, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, TFTP, WS, WSS. Available as of PHP 8.3.0 and cURL 7.85.0.

A string with the HTTP proxy to tunnel requests through. This should be the hostname, the dotted numerical IP address or a numerical IPv6 address written within [brackets]. Available as of cURL 7.1.0.

A bitmask of the HTTP authentication method(s) (CURLAUTH_* constants) to use for the proxy connection. For proxy authentication, only CURLAUTH_BASIC and CURLAUTH_NTLM are currently supported. Defaults to CURLAUTH_BASIC. Available as of cURL 7.10.7.

An array of custom HTTP header strings to pass to proxies. Available as of PHP 7.0.7 and cURL 7.37.0.

Set a string with the password to be used for authentication with the proxy. Available as of cURL 7.19.1.

An int with the port number of the proxy to connect to. This port number can also be set in CURLOPT_PROXY. Setting this to zero makes cURL use the default proxy port number or the port number specified in the proxy URL string. Available as of cURL 7.1.0.

Sets the type of the proxy to one of the CURLPROXY_* constants. Defaults to CURLPROXY_HTTP. Available as of cURL 7.10.

Set a string with the username to be used for authentication with the proxy. Available as of cURL 7.19.1.

A string with a username and password formatted as [username]:[password] to use for the connection to the proxy. Available as of cURL 7.1.0.

The path to proxy Certificate Authority (CA) bundle. Set the path as a string naming a file holding one or more certificates to verify the HTTPS proxy with. This option is for connecting to an HTTPS proxy, not an HTTPS server. Defaults set to the system path where cURL's cacert bundle is assumed to be stored. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the name of a PEM file holding one or more certificates to verify the HTTPS proxy with. This option is for connecting to an HTTPS proxy, not an HTTPS server. Defaults set to the system path where cURL's cacert bundle is assumed to be stored. Available as of PHP 8.2.0 and cURL 7.77.0.

A string with the directory holding multiple CA certificates to verify the HTTPS proxy with. Available as of PHP 7.3.0 and cURL 7.52.0.

Set to a string with the file name with the concatenation of CRL (Certificate Revocation List) in PEM format to use in the certificate validation that occurs during the SSL exchange. Available as of PHP 7.3.0 and cURL 7.52.0.

Proxy issuer SSL certificate filename string. Available as of PHP 8.1.0 and cURL 7.71.0.

A string with the proxy issuer SSL certificate. Available as of PHP 8.1.0 and cURL 7.71.0.

Set the string be used as the password required to use the CURLOPT_PROXY_SSLKEY private key. A passphrase is not needed to load a certificate but one is needed to load a private key. This option is for connecting to an HTTPS proxy, not an HTTPS server. Available as of PHP 7.3.0 and cURL 7.52.0.

Set the pinned public key for HTTPS proxy. The string can be the file name of the pinned public key which is expected to be in a PEM or DER file format. The string can also be any number of base64 encoded sha256 hashes preceded by sha256// and separated by ;. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the proxy authentication service name. Available as of PHP 7.0.7, cURL 7.43.0 (for HTTP proxies) and cURL 7.49.0 (for SOCKS5 proxies).

A string with the file name of the client certificate used to connect to the HTTPS proxy. The default format is P12 on Secure Transport and PEM on other engines, and can be changed with CURLOPT_PROXY_SSLCERTTYPE. With NSS or Secure Transport, this can also be the nickname of the certificate used for authentication as it is named in the security database. If a file from the current directory is to be used, it must be prefixed with ./ in order to avoid confusion with a nickname. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the format of the client certificate used when connecting to an HTTPS proxy. Supported formats are PEM and DER, except with Secure Transport. OpenSSL (versions 0.9.3 and later) and Secure Transport (on iOS 5 or later, or OS X 10.7 or later) also support P12 for PKCS#12-encoded files. Defaults to PEM. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the SSL proxy client certificate. Available as of PHP 8.1.0 and cURL 7.71.0.

A string with the file name of the private key used for connecting to the HTTPS proxy. The default format is PEM and can be changed with CURLOPT_PROXY_SSLKEYTYPE. (iOS and Mac OS X only) This option is ignored if cURL was built against Secure Transport. Available if built with TLS enabled. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the format of the private key. Supported formats are: PEM, DER, ENG. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with the private key for connecting to the HTTPS proxy. Available as of PHP 8.1.0 and cURL 7.71.0.

Set the preferred HTTPS proxy TLS version to one of the CURL_SSLVERSION_* constants. Defaults to CURL_SSLVERSION_DEFAULT.

A string with a colon-separated list of ciphers to use for the connection to the HTTPS proxy. When used with OpenSSL commas and spaces are also acceptable as separators, and !, - and + can be used as operators. Available as of PHP 7.3.0 and cURL 7.52.0.

Set proxy SSL behavior options, which is a bitmask of the CURLSSLOPT_* constants. Available as of PHP 7.3.0 and cURL 7.52.0.

Set to 2 to verify in the HTTPS proxy's certificate name fields against the proxy name. When set to 0 the connection succeeds regardless of the names used in the certificate. Use that ability with caution! Set to 1 in cURL 7.28.0 and earlier as a debug option. Set to 1 in cURL 7.28.1 to 7.65.3 CURLE_BAD_FUNCTION_ARGUMENT is returned. As of cURL 7.66.0 1 and 2 is treated as the same value. Defaults to 2. In production environments the value of this option should be kept at 2. Available as of PHP 7.3.0 and cURL 7.52.0.

Set to false to stop cURL from verifying the peer's certificate. Alternate certificates to verify against can be specified with the CURLOPT_CAINFO option or a certificate directory can be specified with the CURLOPT_CAPATH option. When set to false, the peer certificate verification succeeds regardless. true by default. Available as of PHP 7.3.0 and cURL 7.52.0.

A string with a colon-separated list of ciphers to use for the connection to the TLS 1.3 connection to a proxy. This option is currently used only when cURL is built to use OpenSSL 1.1.1 or later. When using a different SSL backend the TLS 1.3 cipher suites can be set with the CURLOPT_PROXY_SSL_CIPHER_LIST option. Available as of PHP 7.3.0 and cURL 7.61.0.

A string with the password to use for the TLS authentication method specified with the CURLOPT_PROXY_TLSAUTH_TYPE option. Requires that the CURLOPT_PROXY_TLSAUTH_USERNAME option to also be set. Available as of PHP 7.3.0 and cURL 7.52.0.

The method of the TLS authentication used for the HTTPS connection. Supported method is SRP.

Note:

Secure Remote Password (SRP) authentication for TLS provides mutual authentication if both sides have a shared secret. To use TLS-SRP, the CURLOPT_PROXY_TLSAUTH_USERNAME and CURLOPT_PROXY_TLSAUTH_PASSWORD options must also be set.

The username to use for the HTTPS proxy TLS authentication method specified with the CURLOPT_PROXY_TLSAUTH_TYPE option. Requires that the CURLOPT_PROXY_TLSAUTH_PASSWORD option to also be set. Available as of PHP 7.3.0 and cURL 7.52.0.

Set to 1 to set the transfer mode (binary or ASCII) for FTP transfers done via an HTTP proxy, by appending type=a or type=i to the URL. Without this setting or it being set to 0, CURLOPT_TRANSFERTEXT has no effect when doing FTP via a proxy. Defaults to 0. Available as of cURL 7.18.0.

true to HTTP PUT a file. The file to PUT must be set with CURLOPT_READDATA and CURLOPT_INFILESIZE. Available as of cURL 7.1.0 and deprecated as of cURL 7.12.1.

Set to true for cURL to skip cleanup of resources when recovering from a timeout. This allows for a swift termination of the cURL process at the expense of a possible leak of associated resources. Available as of PHP 8.3.0 and cURL 7.87.0.

An array of FTP command strings to execute on the server prior to the FTP request. Available as of cURL 7.1.0.

A string with a filename to be used to seed the random number generator for SSL. Available as of cURL 7.7.0 and deprecated as of cURL 7.84.0.

A string with the range(s) of data to retrieve in the format X-Y where X or Y are optional. HTTP transfers also support several intervals, separated with commas in the format X-Y,N-M. Set to null to disable requesting a byte range. Available as of cURL 7.1.0.

Sets a file pointer resource that will be used by the file read function set with CURLOPT_READFUNCTION. Available as of cURL 7.9.7.

A callable with the following signature:

curlHandle

The cURL handle.

streamResource

Stream resource provided to cURL through the option CURLOPT_READDATA.

maxAmountOfDataToRead

The maximum amount of data to be read.

Bitmask of CURLPROTO_* values which limit what protocols cURL may use in a transfer that it follows to in a redirect when CURLOPT_FOLLOWLOCATION is enabled. This allows limiting specific transfers to only be allowed to use a subset of protocols in redirections. As of cURL 7.19.4, by default cURL will allow all protocols except for FILE and SCP. Prior to cURL 7.19.4, cURL would unconditionally follow to all supported protocols. See also CURLOPT_PROTOCOLS for protocol constant values. Available as of cURL 7.19.4 and deprecated as of cURL 7.85.0.

Set to a string with a comma separated list of case insensitive protocol names (URL schemes) to allow to follow to in a redirect when CURLOPT_FOLLOWLOCATION is enabled. Set to ALL to enable all protocols. As of cURL 7.65.2 it defaults to FTP, FTPS, HTTP and HTTPS. From cURL 7.40.0 to 7.65.1, this defaults to all protocols except FILE, SCP, SMB and SMBS. Prior to cURL 7.40.0, this defaults to all protocols except FILE and SCP. Available protocols are: DICT, FILE, FTP, FTPS, GOPHER, GOPHERS, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S, RTMP, RTMPE, RTMPS, RTMPT, RTMPTE, RTMPTS, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, TFTP, WS, WSS. Available as of PHP 8.3.0 and cURL 7.85.0.

A string with the contents of the Referer: header to be used in a HTTP request. Available as of cURL 7.1.0.

A string to use in the upcoming request instead of the path as extracted from the URL. Available as of PHP 7.3.0 and cURL 7.55.0.

Provide an array of colon-separated strings with custom addresses for specific host and port pairs in the following format: array( "example.com:80:127.0.0.1", "example2.com:443:127.0.0.2", ) Available as of cURL 7.21.3.

The offset, in bytes, to resume a transfer from. This option accepts any value that can be cast to a valid int. Available as of cURL 7.1.0.

true to return the transfer as a string of the return value of curl_exec() instead of outputting it directly.

Set an int with the CSEQ number to issue for the next RTSP request. Useful if the application is resuming a previously broken connection. The CSEQ increments from this new number henceforth. Defaults to 0. Available as of cURL 7.20.0.

Sets the kind of RTSP request to make. Must be one of the CURL_RTSPREQ_* constants. Available as of cURL 7.20.0.

Set an int with the CSEQ number to expect for the next RTSP Server to Client request. This feature (listening for Server requests) is unimplemented. Defaults to 0. Available as of cURL 7.20.0.

Set a string with the value of the current RTSP Session ID for the handle. Once this value is set to any non-null value, cURL returns CURLE_RTSP_SESSION_ERROR if the ID received from the server does not match. If set to null, cURL automatically sets the ID the first time the server sets it in a response. Defaults to null Available as of cURL 7.20.0.

Sets a string with the stream URI to operate on. If not set, cURL defaults to operating on generic server options by passing * in the place of the RTSP Stream URI. When working with RTSP, CURLOPT_RTSP_STREAM_URI indicates what URL to send to the server in the request header while the CURLOPT_URL indicates where to make the connection to. Available as of cURL 7.20.0.

Set the Transport: header for this RTSP session. Available as of cURL 7.20.0.

Always true, what disables support for the @ prefix for uploading files in CURLOPT_POSTFIELDS, which means that values starting with @ can be safely passed as fields. CURLFile may be used for uploads instead.

The authorization identity (authzid) string for the transfer. Only applicable to the PLAIN SASL authentication mechanism where it is optional. When not specified, only the authentication identity (authcid) as specified by the username will be sent to the server, along with the password. The server will derive the authzid from the authcid when not provided, which it will then use internally. Available as of PHP 8.2.0 and cURL 7.66.0.

true to enable sending the initial response in the first packet. Available as of PHP 7.0.7 and cURL 7.31.0.

A string with the authentication service name. Available as of PHP 7.0.7 and cURL 7.43.0.

A result of curl_share_init(). Makes the cURL handle to use the data from the shared handle. Available as of cURL 7.10.

The SOCKS5 authentication method(s) to use. The options are: CURLAUTH_BASIC, CURLAUTH_GSSAPI, CURLAUTH_NONE. When more than one method is set, cURL will poll the server to see what methods it supports and pick the best one. Defaults to CURLAUTH_BASIC|CURLAUTH_GSSAPI. Set the actual username and password with the CURLOPT_PROXYUSERPWD option. Available as of PHP 7.3.0 and cURL 7.55.0.

Set to 1 to enable and 0 to disable the unprotected exchange of the protection mode negotiation as part of the GSSAPI negotiation. Available as of cURL 7.19.4.

Set a string holding the name of the SOCKS5 service. Defaults to rcmd. Available as of cURL 7.19.4 and deprecated as of cURL 7.49.0. Use CURLOPT_PROXY_SERVICE_NAME instead.

A bitmask consisting of one or more of the following constants: CURLSSH_AUTH_PUBLICKEY, CURLSSH_AUTH_PASSWORD, CURLSSH_AUTH_HOST, CURLSSH_AUTH_KEYBOARD, CURLSSH_AUTH_AGENT, CURLSSH_AUTH_ANY. Defaults to CURLSSH_AUTH_ANY. Available as of cURL 7.16.1.

true to enable, false to disable built-in SSH compression. Note that the server can disregard this request. Defaults to false. Available as of PHP 7.3.0 and cURL 7.56.0.

A callable that will be called when SSH host key verification is needed. The callback must have the following signature:

curlHandle

The cURL handle.

keyType

One of the CURLKHTYPE_* key types.

key

The key to check.

keyLength

The length of the key in bytes.

A string containing 32 hexadecimal digits which should contain the MD5 checksum of the remote host's public key, and cURL will reject the connection to the host unless the md5sums match. This option is only for SCP and SFTP transfers. Available as of cURL 7.17.1.

A string with the base64-encoded SHA256 hash of the remote host's public key. The transfer will fail if the given hash does not match the hash the remote host provides. Available as of PHP 8.2.0 and cURL 7.80.0.

Set to the filename of the known_host file to use which should use the OpenSSH file format as supported by libssh2. Available as of cURL 7.19.6.

The file name for a private key. If not used, cURL defaults to $HOME/.ssh/id_dsa if the HOME environment variable is set, and just id_dsa in the current directory if HOME is not set. If the file is password-protected, set the password with CURLOPT_KEYPASSWD. Available as of cURL 7.16.1.

The file name for a public key. If not used, cURL defaults to $HOME/.ssh/id_dsa.pub if the HOME environment variable is set, and just id_dsa.pub in the current directory if HOME is not set. Available as of cURL 7.16.1.

The name of a file containing a PEM formatted certificate. Available as of cURL 7.1.0.

The password required to use the CURLOPT_SSLCERT certificate. Available as of cURL 7.1.0 and deprecated as of cURL 7.17.0.

A string with the format of the certificate. Supported formats are: PEM, DER, ENG, P12. P12 (for PKCS#12-encoded files) is available as of OpenSSL 0.9.3. Defaults to PEM. Available as of cURL 7.9.3.

A string with the SSL client certificate. Available as of PHP 8.1.0 and cURL 7.71.0.

The string identifier for the crypto engine of the private SSL key specified in CURLOPT_SSLKEY. Available as of cURL 7.9.3.

The string identifier for the crypto engine used for asymmetric crypto operations. Available as of cURL 7.9.3.

The name of a file containing a private SSL key. Available as of cURL 7.9.3.

The secret password needed to use the private SSL key specified in CURLOPT_SSLKEY.

Note:

Since this option contains a sensitive password, remember to keep the PHP script it is contained within safe.

The key type of the private SSL key specified in CURLOPT_SSLKEY. Supported key types are: PEM, DER, ENG. Defaults to PEM. Available as of cURL 7.9.3.

A string private key for client cert. Available as of PHP 8.1.0 and cURL 7.71.0.

One of the CURL_SSLVERSION_* constants.

A colon-separated string of ciphers to use for the TLS 1.2 (1.1, 1.0) connection. Available as of cURL 7.9.

A colon delimited list of elliptic curve algorithms. For example, X25519:P-521 is a valid list of two elliptic curves. This option defines the client's key exchange algorithms in the SSL handshake, if the SSL backend cURL is built to use supports it. Available as of PHP 8.2.0 and cURL 7.73.0.

false to disable ALPN in the SSL handshake (if the SSL backend cURL is built to use supports it), which can be used to negotiate http2. Available as of PHP 7.0.7 and cURL 7.36.0.

false to disable NPN in the SSL handshake (if the SSL backend cURL is built to use supports it), which can be used to negotiate http2. Available as of PHP 7.0.7 and cURL 7.36.0, and deprecated as of cURL 7.86.0.

true to enable and false to disable TLS false start which is a mode where a TLS client starts sending application data before verifying the server's Finished message. Available as of PHP 7.0.7 and cURL 7.42.0.

Set SSL behavior options, which is a bitmask of the CURLSSLOPT_* constants. Defaults to none of the bits being set. Available as of PHP 7.0.7. and cURL 7.25.0.

Set to 0 to disable and 1 to enable SSL session-ID caching. By default all transfers are done using the cache enabled. Available as of cURL 7.16.0.

2 to verify that a Common Name field or a Subject Alternate Name field in the SSL peer certificate matches the provided hostname. 0 to not check the names. 1 should not be used. In production environments the value of this option should be kept at 2 (default value). Support for value 1 removed in cURL 7.28.1. Available as of cURL 7.8.1.

false to stop cURL from verifying the peer's certificate. Alternate certificates to verify against can be specified with the CURLOPT_CAINFO option or a certificate directory can be specified with the CURLOPT_CAPATH option. Defaults to true as of cURL 7.10. Default bundle of CA certificates installed as of cURL 7.10. Available as of cURL 7.4.2.

true to enable and false to disable verification of the certificate's status. Available as of PHP 7.0.7 and cURL 7.41.0.

Accepts a file handle resource pointing to an alternative location to output errors to instead of STDERR. Available as of cURL 7.1.0.

Set the numerical stream weight (a number between 1 and 256). Available as of PHP 7.0.7 and cURL 7.46.0.

true to suppress proxy CONNECT response headers from the user callback functions CURLOPT_HEADERFUNCTION and CURLOPT_WRITEFUNCTION, when CURLOPT_HTTPPROXYTUNNEL is used and a CONNECT request is made. Defaults to false. Available as of PHP 7.3.0 and cURL 7.54.0.

true to enable and false to disable TCP Fast Open. Available as of PHP 7.0.7 and cURL 7.49.0.

If set to 1, TCP keepalive probes will be sent. The delay and frequency of these probes can be controlled by the CURLOPT_TCP_KEEPIDLE and CURLOPT_TCP_KEEPINTVL options, provided the operating system supports them. If set to 0 (default) keepalive probes are disabled. The maximum number of probes can be set with the CURLOPT_TCP_KEEPCNT option. Available as of cURL 7.25.0.

Sets the delay, in seconds, that the operating system will wait while the connection is idle before sending keepalive probes, if CURLOPT_TCP_KEEPALIVE is enabled. Not all operating systems support this option. The default is 60. Available as of cURL 7.25.0.

Sets the interval, in seconds, that the operating system will wait between sending keepalive probes, if CURLOPT_TCP_KEEPALIVE is enabled. Not all operating systems support this option. The default is 60. Available as of cURL 7.25.0.

Sets the maximum number of TCP keep-alive probes. The default is 9. Available as of PHP 8.4.0 and cURL 8.9.0.

true to disable TCP's Nagle algorithm, which tries to minimize the number of small packets on the network. Defaults to true. Available as of cURL 7.11.2.

Set an array of strings to pass to the telnet negotiations. The variables should be in the format >option=value<. cURL supports the options TTYPE, XDISPLOC and NEW_ENV. Available as of cURL 7.7.0.

Set the blocksize to use for TFTP data transmission. Valid range is 8-65464 bytes. The default of 512 bytes is used if this option is not specified. The specified block size is only used if supported by the remote server. If the server does not return an option acknowledgment or returns an option acknowledgment with no block size, the default of 512 bytes is used. Available as of cURL 7.19.4.

true to not send TFTP options requests. Defaults to false. Available as of PHP 7.0.7 and cURL 7.48.0.

Set how CURLOPT_TIMEVALUE is treated. Use CURL_TIMECOND_IFMODSINCE to return the page only if it has been modified since the time specified in CURLOPT_TIMEVALUE. If it hasn't been modified, a 304 Not Modified header will be returned assuming CURLOPT_HEADER is true. Use CURL_TIMECOND_IFUNMODSINCE for the reverse effect. Use CURL_TIMECOND_NONE to ignore CURLOPT_TIMEVALUE and always return the page. CURL_TIMECOND_NONE is the default. Prior to cURL 7.46.0 the default was CURL_TIMECOND_IFMODSINCE. Available as of cURL 7.1.0.

The maximum number of seconds to allow cURL functions to execute. Defaults to 0, meaning that functions never time out during transfer. Available as of cURL 7.1.0.

The maximum number of milliseconds to allow cURL functions to execute. If cURL is built to use the standard system name resolver, that portion of the connect will still use full-second resolution for timeouts with a minimum timeout allowed of one second. Defaults to 0, meaning that functions never time out during transfer. Available as of cURL 7.16.2.

The time in seconds since January 1st, 1970. The time will be used by CURLOPT_TIMECONDITION. Defaults to 0. Available as of cURL 7.1.0.

The time in seconds since January 1st, 1970. The time will be used by CURLOPT_TIMECONDITION. Defaults to zero. The difference between this option and CURLOPT_TIMEVALUE is the type of the argument. On systems where 'long' is only 32 bit wide, this option has to be used to set dates beyond the year 2038. Available as of PHP 7.3.0 and cURL 7.59.0.

A string with a colon-separated list of ciphers to use for the connection to the TLS 1.3 connection. This option is currently used only when cURL is built to use OpenSSL 1.1.1 or later. When using a different SSL backend the TLS 1.3 cipher suites can be set with the CURLOPT_SSL_CIPHER_LIST option. Available as of PHP 7.3.0 and cURL 7.61.0.

Set a password to use for the TLS authentication method specified with the CURLOPT_TLSAUTH_TYPE option. Requires that the CURLOPT_TLSAUTH_USERNAME option also be set. This feature relies on TLS SRP which does not work with TLS 1.3. Available as of cURL 7.21.4.

Set a string with the method of the TLS authentication. Supported method is SRP (TLS Secure Remote Password authentication). Available as of cURL 7.21.4.

Set a string with the username to use for the TLS authentication method specified with the CURLOPT_TLSAUTH_TYPE option. Requires that the CURLOPT_TLSAUTH_PASSWORD option also be set. This feature relies on TLS SRP which does not work with TLS 1.3. Available as of cURL 7.21.4.

Set to 1 to enable and 0 to disable requesting compressed Transfer Encoding in the outgoing HTTP request. If the server responds with a compressed Transfer Encoding, cURL will automatically uncompress it on reception. Defaults to 0. Available as of cURL 7.21.6.

true to use ASCII mode for FTP transfers. For LDAP, it retrieves data in plain text instead of HTML. On Windows systems, it will not set STDOUT to binary mode. Defaults to false. Available as of cURL 7.1.1.

Enables the use of Unix domain sockets as connection endpoint and sets the path to the given string. Set to null to disable. Defaults to null. Available as of PHP 7.0.7 and cURL 7.40.0.

true to keep sending the username and password when following locations (using CURLOPT_FOLLOWLOCATION), even when the hostname has changed. Defaults to false. Available as of cURL 7.10.4.

Some protocols have "connection upkeep" mechanisms. These mechanisms usually send some traffic on existing connections in order to keep them alive. This option defines the connection upkeep interval. Currently, the only protocol with a connection upkeep mechanism is HTTP/2. When the connection upkeep interval is exceeded, an HTTP/2 PING frame is sent on the connection. Defaults to CURL_UPKEEP_INTERVAL_DEFAULT which is currently 60 seconds. Available as of PHP 8.2.0 and cURL 7.62.0.

true to prepare for and perform an upload. Defaults to false. Available as of cURL 7.1.0.

Preferred buffer size in bytes for the cURL upload buffer. The upload buffer size by default is 64 kilobytes. The maximum buffer size allowed to be set is 2 megabytes. The minimum buffer size allowed to be set is 16 kilobytes. Available as of PHP 8.2.0 and cURL 7.62.0.

The URL to fetch. This can also be set when initializing a session with curl_init(). Available as of cURL 7.1.0.

Sets the desired level of SSL/TLS for the transfer when using FTP, SMTP, POP3, IMAP, etc. These are all protocols that start out plain text and get "upgraded" to SSL using the STARTTLS command. Set to one of the CURLUSESSL_* constants. Available as of cURL 7.17.0.

The contents of the User-Agent: header to be used in a HTTP request. Available as of cURL 7.1.0.

The user name to use in authentication. Available as of cURL 7.19.1.

A username and password formatted as [username]:[password] to use for the connection. Available as cURL 7.1.0.

true to output verbose information. Writes output to STDERR, or the file specified using CURLOPT_STDERR. Defaults to false. Available as of cURL 7.1.0.

Set to 1 to transfer multiple files according to a filename pattern. The pattern can be specified as part of the CURLOPT_URL option, using an fnmatch-like pattern (Shell Pattern Matching) in the last part of URL (filename). Available as of cURL 7.21.0.

A callable with the following signature:

curlHandle

The cURL handle.

data

The data to be written.

Accepts a file handle resource to the file that the header part of the transfer is written to. Available as of cURL 7.1.0.

Accepts a bitmask setting WebSocket behavior options. The only available option is CURLWS_RAW_MODE. Defaults to 0. Available as of PHP 8.3.0 and cURL 7.86.0.

A callable with the following signature:

curlHandle

The cURL handle.

bytesToDownload

The total number of bytes expected to be downloaded in this transfer.

bytesDownloaded

The number of bytes downloaded so far.

bytesToUpload

The total number of bytes expected to be uploaded in this transfer.

bytesUploaded

The number of bytes uploaded so far.

A timeout in seconds cURL will wait for a response from an FTP, SFTP, IMAP, SCP, SMTP, or a POP3 server. This option replaces the existing CURLOPT_FTP_RESPONSE_TIMEOUT option which is deprecated in cURL 7.85.0. Available as of PHP 8.4.0.

Specifies the OAuth 2.0 access token. Set to null to disable. Defaults to null. Available as of PHP 7.0.7 and cURL 7.33.0.

A callable with the following signature that gets called after the connection is established, but before the request payload (for example, the GET/POST/DELETE request of an HTTP connection) is sent, and can be used to abort or allow the connection depending on the source and destination IP address and port numbers:

curlHandle

The cURL handle.

destination_ip

The primary IP of the remote server established with this connection. For FTP, this is the IP for the control connection. IPv6 addresses are represented without surrounding brackets.

local_ip

The originating IP for this connection. IPv6 addresses are represented without surrounding brackets.

destination_port

The primary port number on the remote server established with this connection. For FTP, this is the port for the control connection. This can be a TCP or a UDP port number depending on the protocol.

local_port

The originating port number for this connection. This can be a TCP or a UDP port number depending on the protocol.

Available as of PHP 8.4.0. This option requires CURLOPT_VERBOSE option enabled. A callable to replace the standard cURL verbose output. This callback gets called during various stages of the request with verbose debug information. The callback should match the following signature:

curlHandle

The cURL handle.

type

One of the following constants indicating the type of the data value:

Constants	Description
CURLINFO_TEXT (int)	Informational text.
CURLINFO_HEADER_IN (int)	Header (or header-like) data received from the peer.
CURLINFO_HEADER_OUT (int)	Header (or header-like) data sent to the peer.
CURLINFO_DATA_IN (int)	Unprocessed protocol data received from the peer. Even if the data is encoded or compressed, it is not provided decoded nor decompressed to this callback.
CURLINFO_DATA_OUT (int)	Protocol data sent to the peer.
CURLINFO_SSL_DATA_IN (int)	SSL/TLS (binary) data received from the peer.
CURLINFO_SSL_DATA_OUT (int)	SSL/TLS (binary) data sent to the peer.

data

Verbose debug data of the type indicate by the type parameter.

Pass a callable that will be registered to handle server pushes and should have the following signature:

parent_ch

The parent cURL handle (the request the client made).

pushed_ch

A new cURL handle for the pushed request.

headers

The push promise headers.