WhatisCORS(Cross-OriginResourceSharing)?
Software Development Glossary & Terms
CORS (Cross-Origin Resource Sharing)
Definition.
CORS (Cross-Origin Resource Sharing): A mechanism that allows restricted resources on a web page to be requested from another domain outside the domain from which the first resource was served.
In More Detail
CORS is a browser rule, not a server one. The server can serve anyone; the browser refuses to hand a cross-origin response back to JavaScript unless the response headers explicitly allow that origin. This is why the same request works from curl or Postman and fails in the browser, which confuses people the first time.
It shows up the moment a frontend and API live on different domains — a Next.js app calling a separately hosted Django API is the usual case. The fix is to list the exact allowed origins on the server rather than wildcarding them, because a wildcard plus credentials is precisely the combination the rule exists to prevent.
In Practice
This is usually the error that shows up the first time a Next.js frontend tries to talk to a separately-hosted Django API — getting the allowed-origins list right (and not just wildcarding it) is a small but easy-to-get-wrong step in any decoupled frontend/backend setup.
Related Terms
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