Whose side is the problem with JWT authorization and CORS?

Question

JavaScript

I have never done JWT authorization before. I was given a site, login and password for jwt authorization. I do authorization via Xhr, I get the error

"Access to XMLHttpRequest at ' https://blablabla.ru/ ' from origin ' localhost:3000 ' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource."

On which side is this blocking? From my browser or from the site?

Answer 1

From the server side. Does not return the Access-Control-Allow-Origin header