Why Your AI API Throws CORS Errors (And What to Do About It)

Short summary

CORS errors block browser requests to AI APIs because of same-origin policy enforcement—a critical security feature. The wrong approach is exposing API keys in frontend code; the right architecture is browser→backend→AI provider, with your backend handling preflight OPTIONS requests, rate limiting, and secure key management. Includes a production-ready Python/Flask proxy example with token bucket rate limiting.

• •CORS errors occur when browsers block cross-origin requests to AI APIs due to same-origin policy enforcement
• •Never expose API keys in frontend—use a backend proxy architecture instead
• •Working Python/Flask example includes preflight handling, rate limiting, and proper Access-Control-Allow headers

Generated with AI, which can make mistakes.