Preflight

If you call the Wix API from browser JavaScript, CORS is the gatekeeper. When it’s configured the way your frontend needs, everything feels normal. When it isn’t, you get the classic useless browser error: blocked by CORS policy. This guide is the version I wish I had the first time I tried wiring a frontend directly to a third-party API. What CORS means for Wix API CORS stands for Cross-Origin Resource Sharing. Browsers enforce it when your page on one origin tries to call an API on another origin. ...

Every time your React app sends a JSON POST request, the browser does something you might not expect: it sends TWO requests instead of one. The first is an OPTIONS “preflight” request. The second is your actual request. This confuses a lot of people. Why is the browser sending extra requests? Why is my API getting OPTIONS requests I never wrote endpoints for? Why does Postman work but the browser doesn’t? ...