Overview

Checkout is initiated from POST /api/checkout: validates product_id against the pricing page from getPricingPage(locale), then creates an order via insertOrder and either Stripe Checkout or Creem depending on integration config (src/integrations/stripe, src/integrations/creem).

Webhooks & callbacks

Path	Purpose
`/api/pay/callback/stripe`, `/api/pay/notify/stripe`	Stripe return + webhook style handling
`/api/pay/callback/creem`, `/api/pay/notify/creem`	Creem equivalents

Handlers update order status and apply credits through src/models/order.ts, src/models/credit.ts, and src/services/order.ts / credit.ts (idempotent patterns recommended for webhooks).

Credits API

/api/get-user-credits — exposes remaining credits for the logged-in user (used by console/billing UI).

Data flow

Client posts product_id (+ currency, locale).
Checkout route resolves pricing item → builds order row → returns payment provider session/url.
Provider calls back → notify routes verify signature → credits updated → UI refreshes via session or client fetch.

Key files

src/app/api/checkout/route.ts
src/integrations/stripe/index.ts, src/integrations/creem usage
src/services/order.ts, src/services/credit.ts

Dependencies

Environment

PAY_PROVIDER — "stripe" or Creem (see checkout/route.ts).
NEXT_PUBLIC_WEB_URL, NEXT_PUBLIC_PROJECT_NAME, NEXT_PUBLIC_PAY_CANCEL_URL — Stripe/Creem return URLs and branding.
Stripe: STRIPE_PRIVATE_KEY, STRIPE_WEBHOOK_SECRET.
Creem: CREEM_API_KEY, CREEM_ENV, CREEM_PRODUCTS (JSON product map), CREEM_WEBHOOK_SECRET (/api/pay/notify/creem).

Database (src/db/schema.ts)

orders, credits, affiliates

Unconfigured gateways

Checkout returns HTTP 503 with a user-facing availability message when the selected PAY_PROVIDER has no API key (or is unsupported). No order is inserted in this case. Automated gateway tests use a mocked Stripe client; they do not prove live payment settlement.

Payments & credits