Ruby code touches financial transactions. Card payments were migrated to Java when I left in 2022. Non-card payments (e.g., ACH, checks, various wallets) were still processed by Ruby.
PCI-related/vaulting code lived in its own locked-down repo. I think that was a mix of Go and Ruby.
Once you have the foundations in place for account balances and the ledger, processing a payment isn’t that daunting. Those foundations, however, took a lot to build and evolve.
> Once you have the foundations in place for account balances and the ledger, processing a payment isn’t that daunting. Those foundations, however, took a lot to build and evolve.
Pretty much. I've worked at places with PHP payment processing that worked just fine, and at a place with C++ payment processing (and no testers) and it worked just fine. I wasn't around when the systems were first built though so not sure if there were tears along the way.
> migrated to Java
I want to know more about this