What is Curl?
Curl is a command-line tool that allows users to transfer data over the network. Curl supports over 25+ protocols, including HTTP, HTTPS, FTP, FTPS, and SFTP. Curl is used for testing APIs, uploading files, viewing server response content, and has built-in support for web forms, SSL, HTTP Cookies. Curl works on Linux, Mac, Windows.
What is CORS?
CORS (Cross-Origin Resource Sharing) is a security mechanism based on HTTP headers that provide secure communication between browsers and servers running on different origins. CORS allows a web page from one domain or Origin to access a resource with a different domain (a cross-domain request). CORS was implemented due to the limitations of the single-origin policy. The same-origin policy restricts resources to interact only with resources located in the same domain. CORS is a way for the server to check if the request is coming from an allowed origin and tell the browser not to block it.
Curl CORS Request Syntax
To send a CORS request using Curl use the following syntax:
Curl CORS Request Example
An example of sending a CORS request to a ReqBin URL using Curl. To make CORS requests with Curl, you need to provide an Origin header for your requests:
How to debug CORS requests using Curl?
The following are examples of debugging CORS requests using Curl:
Sending a regular CORS request
By sending a regular CORS request with the --verbose flag, the server response will include an Access-Control-Allow-Origin header that can be viewed and analyzed.
Sending a "pre-flight" OPTIONS request
You can send a "pre-flight" OPTIONS request. If the pre-flight request is successful, the response will include the Access-Control-Allow-Origin, Access-Control-Allow-Methods, and Access-Control-Allow-Headers response headers that can be viewed and analyzed.