https://medium.com/coinmonks/how-to-fix-cors-web-server-error-6c2c55938f95 > Cross-Origin Resource Sharing (CORS) is a mechanism that uses additional HTTP headers to tell a browser to let a web application running at one origin (domain) have permission to access selected resources from a server at a different origin. A web application makes a cross-origin HTTP request when it requests a resource that has a different origin (domain, protocol, and port) than its own origin. > In this article, I’m going to show how to fix Access-Control-Allow-Origin error between a Clojure backend web server and an Angular web app frontend in my case.