I tried to grep the code for `api.` to get a sense for all the vendors this codebase is using, and which you'd need to have relationships with to run the code. Here's what I found:
payments:
https://api.paypal.com
https://api.stripe.com
tax stuff:
https://api.taxjar.com
https://api.vatstack.com (EU VAT)
https://apiservices.iras.gov.sg
for iOS app (?):
https://api.appstoreconnect.apple.com
https://api.storekit.itunes.apple
AI stuff:
https://api.iffy.com (AI content moderation)
https://api.helper.ai (AI support)
https://api.openai.com
other:
https://api.easypost.com (shipping labels?)
https://api.sendgrid.com (email)
https://api.pwnedpasswords.com (haveibeenpwned)
https://api.worldbank.org (for purchasing power parity?)
https://api.dropboxapi.com (for "upload from dropbox"?)