In Express.js application the https://www.npmjs.com/package/expect-ct[expect-ct] middleware is the standard way to implement expect-ct. Usually, the deployment of this policy starts with the report only mode (``enforce: false``) and with a low ``maxAge`` (the number of seconds the policy will apply) value and next if everything works well it is recommended to block future connections that violate Expect-CT policy (``enforce: true``) and greater value for maxAge directive: