@neal I find myself building some cart/checkout/e-commerce stuff from (relative) scratch, and I remember you posting about doing so yourself. Were there any particularly useful resources for design there?
@yomimono In my case I was using the Stripe API for payment processing which has excellent documentation (the curl examples are reasonably easy to translate to whatever you want to use for that). The coffee shop additionally uses Shippo for postage rate quotes and label generation. Otherwise, my guiding principle was to keep things pretty much as dumb as possible (but no dumber) and log everything in case I messed it up. Happy to chat if you have questions.