14 · Shipping & Collaboration
CORS
Cross-Origin Resource Sharing
Browser rules that control which websites may call which APIs. A “CORS error” usually means the API did not allow your page’s origin—not that the network cable failed.
Concrete example
A local Vite app on port 5173 calling an API on another host will fail until CORS headers allow it.
Why it matters
One of the most common blockers when an agent wires a frontend to a backend.