Reference
Payments references
Lookup pages for when a payment is failing and you need the exact answer: what a code means, which test value triggers a scenario, what to do next. Not Flint documentation; these cover the payments ecosystem, with a short bridge to how each topic works on Flint.
Card decline codes
Every decline code that matters: what the issuer is saying, whether a retry can work, what to tell the customer, and the network retry rules that make blind retries expensive.
Test card numbers
Every documented test card and failure trigger for Stripe, Square, Adyen, Braintree, PayPal, and Authorize.net, plus the nine cards that matter in every Flint sandbox.
Looking for Flint's own documentation? Start at the docs, the API reference, or the Flint error catalog.