&gt; I wish expiring credit card numbers existed<p>Many banks actually offer exactly this feature. You set a dollar limit and an expiry date. E.g. Bank of America ShopSafe: <a href="https:&#x2F;&#x2F;www.bankofamerica.com&#x2F;privacy&#x2F;accounts-cards&#x2F;shopsafe.go" rel="nofollow">https:&#x2F;&#x2F;www.bankofamerica.com&#x2F;privacy&#x2F;accounts-cards&#x2F;shopsaf...</a> My Swedish bank offers the same thing and even has an app to generate card #s