Production API & Webhook Engineering

Production Third-Party API & Payment Integrations

Connecting external services requires more than calling an endpoint. I build resilient, idempotent, and security-hardened integrations for Stripe, Razorpay, WhatsApp Business API, and Google Maps Platform.

Idempotent WebhooksCryptographic HMAC VerificationReplay Attack Protection
Global SaaS & SubscriptionsPayments & Billing

Stripe & SaaS Billing Integration

Production-grade Stripe integration for SaaS subscriptions, usage-based metering, checkout sessions, customer portal, and idempotent webhook listeners.

Key Engineering Scope:
  • Stripe Checkout & Elements with custom brand theming
  • Tiered, metered, and seat-based SaaS recurring subscriptions
  • Stripe Customer Portal integration for self-serve cancellation and invoice downloads
India Payments & UPIPayments & Billing

Razorpay & Indian UPI Integration

Robust Razorpay payment integration for India: UPI QR, Google Pay, PhonePe, net banking, recurring auto-debit, and HMAC-SHA256 signature verification.

Key Engineering Scope:
  • Custom Razorpay Standard & Custom Checkout integration
  • Native UPI Intent flow for mobile apps (PhonePe, Google Pay, Paytm)
  • Razorpay Route for marketplace multi-vendor fund splits
Conversational AutomationMessaging & Alerts

WhatsApp Business Cloud API

Enterprise WhatsApp Business Cloud API integration for automated order alerts, customer support bots, appointment confirmations, and transactional updates.

Key Engineering Scope:
  • Meta WhatsApp Cloud API setup and system user token management
  • Two-way interactive webhook listener with SHA-256 payload verification
  • Template message submission and parameter mapping (order status, appointment, OTP)
Location & Fleet TrackingGeolocation & Maps

Google Maps Platform & Geolocation

High-performance Google Maps integration: Places autocomplete, geocoding, real-time driver tracking, route optimization, and distance calculations.

Key Engineering Scope:
  • Places Autocomplete with session token optimization to reduce API costs by up to 60%
  • Forward and reverse geocoding with server-side Redis caching
  • Directions API and Distance Matrix for delivery estimation and dispatch routing
Integration Consulting

Need a Production API or Payment Gateway Integration?

Tell me which third-party service, payment processor, or messaging API you need integrated. I will review your requirements and outline a clean, idempotent architecture.

100% IP ownership & clean repository handover
< 24h direct review & scope feedback
NDA signed before proprietary discussion
Milestone-based delivery & 30-day warranty
Discuss Project