Overkill

absurdly advanced tech, explained badly, used for dumb stuff

All overkills

Card payments

or: a global fraud-sniffing network for one latte

You tap a card, and a chip inside it makes up a one-time security code that is only good for this one purchase1. The request races from the store’s bank across a network built to handle more than 65,000 messages a second2 to your bank, while a fraud model weighs more than 500 details about it in about a millisecond3, and the answer comes back before you’ve put your phone away. One network alone does this 258 billion times a year4.

And we use it to buy a latte.

How it works, badly

  1. #
    code: 7Q4X... just this once
    You tap, and the chip makes up a brand new secret code.
  2. #
    storenetworkyour bankzoooom
    It zips through a network built for 65,000 messages a second.
  3. #
    ...500
    A robot checks 500 things in about a millisecond.
  4. #
    approved
    Then we use it to buy a latte.

Wait, is that real?

Yes, all of that happens before the barista finishes the foam.

The tap↩

When you tap a chip card or a phone, the EMV contactless standard has it generate a one-time use security code for that transaction. A thief who copies the data can’t reuse it for another purchase.

The network↩

Visa has said its network, VisaNet, is capable of processing more than 65,000 transaction messages per second. A tap travels from the store’s bank across the network to the bank that issued your card, which says yes or no.

The fraud check↩

Visa says its Advanced Authorization system weighs more than 500 risk attributes for each transaction, each in about one millisecond.

The scale↩

In fiscal 2025, 258 billion transactions were processed by Visa, out of 329 billion Visa-branded payments and cash transactions overall, across nearly 5 billion payment credentials and more than 175 million merchant locations.

The fine print↩

65,000 a second is capacity, not traffic: 258 billion a year works out to roughly 8,000 a second on average. Visa last published that capacity figure in 2017 and 2018, and the 500 attributes come from a 2019 announcement, so today’s numbers are likely higher. Mastercard and others run their own networks; Visa is just the one with the clearest public numbers. And the latte costs the same however fast it was paid for.

Sources: EMVCo: EMV contactless chip; Visa Form 10-K, fiscal 2018 (VisaNet capacity); Visa: fraud prevented with artificial intelligence (2019); Visa Form 10-K, fiscal 2025

Last fact-checked .