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Cloudflare Workers: CORS patterns at the edge
Short-circuit OPTIONS, validate origins in worker code, and keep secrets out of client bundles.
1 min read
cloudflareedgecors
Handle OPTIONS early
Return a fast response for preflight with required Allow-Headers and Allow-Methods lists.
Keep worker CPU low by avoiding heavy crypto on every OPTIONS if possible.
KV and environment bindings
Store allowlists in KV for dynamic updates without redeploying when requirements change.
Bind secrets via wrangler and never inline them in public scripts.