Payment Methods, Wallets & Strong Customer Authentication — Payments & Money APIs

Beyond cards: wallets (Apple Pay, Google Pay — tokenized cards with built-in authentication), bank debits (SEPA Direct Debit, ACH — cheap but slow and reversible), real-time account-to-account (UPI, Pix, FedNow, Faster Payments, open-banking payment initiation), BNPL and many local methods (iDEAL, Bancontact, Konbini). In the EEA/UK, PSD2 Strong Customer Authentication requires two factors for many online payments; for cards that's 3-D Secure 2, which may add a challenge step. Design flows for asynchronous confirmation — many methods confirm minutes or days later.

Payment methods

Method	Confirmation	Reversibility	Cost	Notes
Cards	Seconds (auth)	Chargebacks	Higher % fees	3DS2 for SCA
Wallets	Seconds	Like cards	Card fees	High conversion on mobile
Bank debit (SEPA DD / ACH)	Days	Returns/disputes possible for weeks	Low	Mandates required
Real-time A2A (Pix, UPI, FedNow)	Seconds	Generally final	Low	Push payments; regional
BNPL	Seconds	Provider handles	High merchant fee	Higher AOV
Bank transfer (manual)	Hours–days	Final	Low	Reconciliation via reference

Python (PaymentIntent with automatic methods)

intent = stripe.PaymentIntent.create(
    amount=4999, currency="eur",
    automatic_payment_methods={"enabled": True},    # PSP offers eligible methods (cards, wallets, local)
    metadata={"order_id": "ord_123"},
    idempotency_key="pi:ord_123:v1",
)
# Client confirms with the PSP SDK; 3DS challenges are handled there.
# The intent may end in: succeeded | processing (async methods) | requires_action | requires_payment_method

Common pitfalls

Assuming every payment confirms instantly.
Fulfilling bank debits before the settlement/return window risk is understood.
Building 3DS flows by hand instead of using the PSP SDK.

Key points

Offer local methods where customers are
Design for asynchronous confirmation
SCA/3DS handled by PSP SDKs

Further reading: Stripe: Strong Customer Authentication

Practice questions

What is Strong Customer Authentication?

Answer

A PSD2 requirement (EEA/UK) that many electronic payments be authenticated with two of: knowledge, possession, inherence — for cards typically via 3-D Secure 2.

Why must your order flow handle a 'processing' payment state?

Answer

Methods like bank debits confirm asynchronously, so the payment can be pending for days before succeeding or failing.