curl

Send JSON:

curl -X POST [URL] \
     -H "Content-Type: application/json" \
     -d "[JSON data]"

Simulating a web form:

curl [URL] -d "key1=value1&key2=value2"
curl [URL] -F key1=value1 -F key2=value2 -F key2=@filename

curl -O [URL]

curl -O [URL]

5. Send Cookies with Request

You can use the --cookie "name=value" command line parameter to send cookies to the server with your request. curl will automatically convert this parameter to the Cookie: name=value request HTTP header.

Curl Send Cookies Example

curl --cookie "name=value" [URL]

6. Ignore SSL Certificate Errors

To ignore SSL certificate validation, you can pass the -k or --insecure option to the curl command. This option tells curl to perform “unsecured” SSL connections and file transfers. Data is still transmitted over the SSL encrypted channel, but curl ignores any security warnings about invalid or expired SSL certificates and accepts them as valid.

Curl Disable Certificate Validation Example

curl -k [URL]

7. Get only HTTP Headers

The -I or --head option allows curl to fetch only a specific resource’s HTTP headers (HTTP HEAD method). The HEAD request method is identical to the GET method, except that the server does not return the body of the HTTP message.

Curl Get Only HTTP Headers Example

curl -I https://reqbin.com/echo

8. Download Multiple Files at Once

You can download multiple files in a single curl command by specifying the -O parameter multiple times with the desired URLs. If files are downloaded from the same server, curl will try to reuse the connection.

Curl Download Multiple Files Example

curl -O [URL1] -O [URL2]

9. Do HTTP Authentication

Some websites may require user authentication before providing any content (username and password). You can pass user credentials to the server using the -u command line option. By default, curl uses Basic HTTP Authentication. We can specify other authentication methods using --ntlm or --digest.

Curl HTTP Authentication Example

curl -u username:password [URL]

10. Follow Redirects

By default, curl does not perform 300x redirects. To tell curl to follow HTTP redirects, use the -L or --location command line option. The server provides the new address using the Location HTTP header.

Curl Follow Redirect Example

curl -L [URL]

11. Connect via Proxy Server

To establish a connection through a proxy server, pass the required proxy address using the -x command line parameter. You can pass the username and password for proxy authentication using the -U command line parameter.

Curl Proxy Example

curl -x [protocol://][host][:port] -U user:password [URL]

12. Make Curl Verbose

The -v option makes curl verbose at runtime and asks curl to provide detailed information about the progress of the operation, which can be useful when debugging complex situations.

Curl Verbose Example

curl -v [URL]