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Remix loaders and CORS: single-flight mutations versus cross-origin resource loaders
Same-origin Remix apps call your routes; external APIs still need CORS if fetched from the browser in client code.
1 min read
remixcorsreact
Deployment surfaces
Vercel and Netlify may inject headers differently—verify OPTIONS on each platform.
Edge functions can add CORS centrally but watch cold start latency on preflight.
Streaming
Deferred responses should still emit CORS headers on the initial document if loaders run cross-origin.
Monitor waterfall charts when mixing Remix deferred promises with third-party APIs.