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HTTP headers cheat sheet

The request and response headers that control caching, cross-origin access and browser security, with the values you actually want in production.

Caching

CORS

Security

Content

Things worth remembering

  • Cache-Control: public, max-age=31536000, immutable is correct only for content-hashed filenames.
  • A wildcard Access-Control-Allow-Origin cannot be combined with credentials. Echo the origin instead.
  • Content-Security-Policy is the single highest-value security header. Start in report-only mode.

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