An unexpected charge at checkout — a subscription price increase, a trial that charged you, a purchase you did not approve — is easiest to stop before you click Pay. Decionis Shield checks the amount on a checkout page against the spending limit you set in the Shield app and warns you when it is over. It keeps a signed record of every warning, so you can dispute a charge with proof. Pair with the app in ten seconds: open the extension, choose "Pair with the app", and type the code the app shows. No second sign-in. Shield warns; it cannot stop a payment for you. It reads the amount on checkout pages only, sends nothing else, and never sells your data.