API Design · Junior · Question 54 of 75

Why are CORS preflight `OPTIONS` requests sent?

✓Correct answer: Before 'non-simple' cross-origin requests (e.g. JSON body, custom headers), the browser asks the server which methods and headers are allowed
2To log in
3To measure latency

Explanation

Servers can reduce preflights with Access-Control-Max-Age, which lets browsers cache the answer.

Further reading

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