# CORS

Cross-Origin Resource Sharing ([CORS](https://developer.mozilla.org/en-US/docs/Glossary/CORS))

By default, requests are blocked if not same origin

**SERVER** must be configured to return the resource with the `Access-Control-Allow-Origin: *` or the specific domain you wish to allow

All non idempotent(besides GET and some POSTS with specific meme) will be first fetched with an OPTIONS

Express => https://expressjs.com/en/resources/middleware/cors.html

Flask => https://flask-cors.readthedocs.io/en/latest/#using-json-with-cors

_Sometimes you can get CORS errors because of having/not having a trailing slash (something about redirects not being allowed idk)_
