Five implementation paths · static code guides
Choose your platform, create payment orders from a trusted backend, authenticate webhooks over raw bytes, and reconcile every ambiguous state.
Integration directory
WordPress plugin
Register a WooCommerce payment method, create the order server-side, redirect to hosted checkout, and verify signed callbacks before marking an order paid.
Guide covers
Commerce platform
Choose between Shopify's approved payments-app programme and a transparent manual-payment workflow without claiming unsupported checkout access.
Guide covers
Backend framework
Create a typed payment client with timeouts and idempotency, expose a narrow checkout endpoint, and verify timestamped HMAC events from raw bytes.
Guide covers
Backend framework
Use Decimal-safe request models, an async httpx client, raw FastAPI request bytes, hmac.compare_digest, and a transactional event consumer.
Guide covers
Backend framework
Build a Laravel service class, validate checkout requests, send authenticated API calls, verify hash_hmac signatures, and queue fulfilment after commit.
Guide covers
Shared architecture
The X-API-Key and webhook secret never enter browser JavaScript, a mobile package, Shopify theme code, WordPress markup, URLs, or analytics.
Your server loads the cart and calculates the expected integer-paise total. A browser-supplied amount is never accepted as payment truth.
The customer-facing redirect can display pending status, but only a verified server event or authenticated status response can drive fulfilment.
Reuse one client_txn_id when a create request times out. Store a unique event key before applying a payment transition.
Canonical event flow
All five guides implement the same trust model. The framework adapters change, but browser input remains untrusted and order state remains server-owned.
browser → merchant checkout endpoint
→ validate cart and amount
→ create_order (X-API-Key)
← hosted URL / QR / UPI intent
provider → signed merchant webhook
→ verify timestamp + raw body
→ match order + amount + currency
→ idempotent database transition
→ asynchronous fulfilmentBefore writing framework code