6 ms·

That’s volume in terms of total payments, but in terms of number of API requests it’s surprisingly little. I used to work in payments myself and I was shocked

That’s volume in terms of total payments, but in terms of number of API requests it’s surprisingly little. I used to work in payments myself and I was shocked by how little the throughout is in terms of actual transactions per second. There simply aren’t that many payments happening globally at any moment, especially when compared to other industries. A single games company can be doing far more API requests than the total volume of payments happening concurrently in the world, ditto for ads companies or observability companies. At a payments company, 500 payments per second is considered high throughput and 1000 payments per second is a huge amount of volume. I’ve worked at games companies where 5000 transactions per second is low throughput. The hard part in payments companies is consistency and reliability and “correctness”, the actual load and volume is embarrassingly small.

ElFitz 1mo ago
> At a payments company, 500 payments per second is considered high throughput and 1000 payments per second is a huge amount of volume. I realise I live in a strange world when my first thought reading this is "Worldwide? That’s low. Fits in the basic one region, one account concurrent AWS Lambda quota. No need to even ask support for the 10k."
- Wololooo 1mo ago
  I mean, if you think about it, you can't pay a lot per second, most of people don't have money to throw around that much... How many times do you buy things during a day? Once? twice? Maybe thrice? 6 million payment uniformly in an hour is 1666 transactions per second, overall this tracks.
  - ElFitz 1mo ago
    Makes sense. Probably how one would approach it during a system design interview. > How many times do you buy things during a day? Once? twice? Maybe thrice? None most days. But then some days eight or nine subscriptions go through. Guess it averages out. Might be spiky though, around the beginning and ends of each month. If paying out wages monthly, and at the end of the month or beginning of the next one is prevalent across countries where a significant share of the population has both access to a bank account and sufficient enough income to regularly spend either by card or online. Did this turn into a systems design interview? Anyway, joking aside, I was mostly amused by what my frame of reference for throughput / service load has become.
    - saberience 28d ago
      Yes it's not very intuitive and surprised me a lot when I went into payments. And let me state again, if you're a payments processor and you're processing 500-1000 payments PER SECOND on average, that makes you a very big company indeed (multi billion dollar company). You can do the math, work out how many payments that is, what an average value of payment is, and what the TPV would be for a month. You can easily run into huge numbers that way. And don't forget, the payment processors are taking percentages in most cases, so that 120 payments per second can turn into a huge amount of revenue at the end of the month.

ElFitz 1mo ago

> At a payments company, 500 payments per second is considered high throughput and 1000 payments per second is a huge amount of volume. I realise I live in a strange world when my first thought reading this is "Worldwide? That’s low. Fits in the basic one region, one account concurrent AWS Lambda quota. No need to even ask support for the 10k."

Wololooo 1mo ago
I mean, if you think about it, you can't pay a lot per second, most of people don't have money to throw around that much... How many times do you buy things during a day? Once? twice? Maybe thrice? 6 million payment uniformly in an hour is 1666 transactions per second, overall this tracks.
- ElFitz 1mo ago
  Makes sense. Probably how one would approach it during a system design interview. > How many times do you buy things during a day? Once? twice? Maybe thrice? None most days. But then some days eight or nine subscriptions go through. Guess it averages out. Might be spiky though, around the beginning and ends of each month. If paying out wages monthly, and at the end of the month or beginning of the next one is prevalent across countries where a significant share of the population has both access to a bank account and sufficient enough income to regularly spend either by card or online. Did this turn into a systems design interview? Anyway, joking aside, I was mostly amused by what my frame of reference for throughput / service load has become.
  - saberience 28d ago
    Yes it's not very intuitive and surprised me a lot when I went into payments. And let me state again, if you're a payments processor and you're processing 500-1000 payments PER SECOND on average, that makes you a very big company indeed (multi billion dollar company). You can do the math, work out how many payments that is, what an average value of payment is, and what the TPV would be for a month. You can easily run into huge numbers that way. And don't forget, the payment processors are taking percentages in most cases, so that 120 payments per second can turn into a huge amount of revenue at the end of the month.