
Ask HN: Do you have a custom-payment-system horror story? - ezekg
You always hear that it&#x27;s usually a bad idea to write a custom payment system. Let&#x27;s share why.<p><pre><code>    - Maybe you charged your users multiple times?
    - Or charged somebody way too much?
</code></pre>
Let&#x27;s hear it!
======
posguy
Man, I've got some stories. A few years back, circa 2014 I installed & set up
PCAmerica CRE for a business. We used Ingenico ISC250 pinpads with direct
integration which turned out to be a very poor decision! For a span of a
month, those damn pinpads randomly double charged debit & EBT customers (which
we reversed in bulk afterward), and the building got tagged saying "You stole
$20 off my EBT Card". Ended up swapping in FD35 pinpads, but the damage was
done.

Another time, I was down in Cali visiting family. Stopped in at the 7-Eleven
caddy corner to where I was staying, and accidentally pulled a shim out of the
Ingenico ISC350 that was sitting on the counter. What a joy! From what I hear,
that 7-Eleven still has issues with that type of stuff, so much so that my
family started paying in cash.

Also met some guys who were working on this pinpad integration for Pax,
sounded like the API was designed back in the serial days (with the
limitations that entails) and they were trying to make the best of it. Items
onscreen worked, but you couldn't display the live total, Pax had designed
their own coordinate pair protocol instead of sending a SVG of the customer's
signature, etc. IIRC this is the library they published:
[https://github.com/AccelerateNetworks/PHPax](https://github.com/AccelerateNetworks/PHPax)

