Fintech Software & Custom Payment Solutions in Kerala
Razorpay · Stripe · UPI Intent · Cryptographic HMAC Webhooks · Zero-Loss Idempotency
Custom fintech and payment gateway engineering in Kerala by Senior Solution Architect Abin S Chandran. Razorpay, Stripe, UPI Intent flows, HMAC cryptographic webhooks, and automated ledger reconciliation.
Modular Capabilities & Engineering Standards
Every system is engineered from the ground up for high performance, zero vendor lock-in, and rapid return on investment:
Native UPI Intent & High-Conversion Checkout Flows
Zero-redirect UPI deep links (Google Pay, PhonePe, Paytm, CRED) directly embedded inside Next.js 15 and Flutter checkout experiences to eliminate cart drop-offs.
- Native UPI Intent SDK integration for mobile and web
- Dynamic QR generation with automatic payment state listeners
- Saved cards tokenization in compliance with RBI guidelines
- Instant OTP and 3D Secure auto-read verification flows
Idempotent Ledger & Cryptographic Webhook Ingestion
Asynchronous event pipelines that verify HMAC-SHA256 signatures, prevent duplicate transaction processing during network retries, and guarantee double-entry accounting integrity.
- Cryptographically verified webhook endpoints with replay attack defense
- Redis-backed distributed transaction locks for strict idempotency
- PostgreSQL transactional ledger records with ACID guarantees
- Automated fallback webhooks querying aggregator APIs on timeout
Multi-Currency Global Processing & Diaspora Payouts
Stripe, PayPal, and international wire integration for SaaS platforms, exporters, and NRI services accepting USD, EUR, GBP, and AED with automatic FX rate conversion.
- Dynamic currency conversion (DCC) and localization
- Automated GST/tax invoicing and export compliance reporting
- Automated subscription recurring billing and smart dunning flows
- Cross-border payment dispute and chargeback defense logging
Automated Financial Reconciliation & Escrow Sync
Scheduled batch reconciliation matching gateway settlement logs against internal orders, identifying fee discrepancies, and automating vendor commission split payouts.
- Automated daily bank settlement vs gateway log reconciliation
- Multi-party marketplace split payouts (Razorpay Route / Stripe Connect)
- Automated instant refund processing with webhook confirmation
- Exportable audit-ready financial ledger summaries (CSV/JSON/PDF)
Real-World Architecture in Production
MSME Growth CRM & Lead Automation Engine
Multi-tenant B2B enterprise platform serving Kerala and Middle East enterprises with zero per-seat software licensing fees.
Solo Solution Architect vs. Agency Bloat
Compare direct engineering ownership with typical software agencies:
| Dimension | Abin S Chandran (Direct) | Traditional Regional Agency | Off-The-Shelf SaaS |
|---|---|---|---|
| Direct Communication | 1:1 Direct with Senior Architect | Filtered via non-technical account managers | Impersonal chatbot ticket queues |
| Code & IP Ownership | 100% Full IP & Git repo handover | Often locked in proprietary agency modules | 0% ownership (Vendor locked in forever) |
| Monthly License Fees | ₹0/month (Fixed one-time build) | Expensive monthly retainer contracts | ₹2,500–₹8,000/seat/month recurring tax |
| Turnaround Speed | 2 to 4 weeks production MVP | 3 to 6 months with endless change orders | Days to set up, but rigid & unadaptable |
From Discovery to Production Deployment
Discovery & Spec
48-hour deep dive into business workflows, edge cases, schema requirements, and API dependencies.
Data & API Architecture
Relational schema design, RBAC permission matrices, cryptographic HMAC signature verifications.
Milestone Sprints
Rapid 14-day production sprints with live staging demo environments, automated tests, and client review.
Launch & Warranty
Production DNS cutover, zero-downtime deployment, 30-day warranty, and 100% code handover.
Frequently Asked Questions
How do you prevent double-charging or lost transactions during network timeouts?+
We implement strict idempotency keys generated at checkout initiation. When a payment gateway retries a webhook or a user taps pay twice, the distributed Redis cache verifies the unique request token, ensuring the transaction executes exactly once and duplicate callbacks are safely acknowledged without re-charging.
Which payment aggregators do you recommend for Indian startups and SaaS platforms?+
For domestic Indian transactions (UPI and NetBanking), Razorpay and Cashfree deliver the highest conversion rates and lowest latency. For global international recurring billing and diaspora buyers, Stripe combined with automated GST export compliance is our gold standard.
Do we need full PCI-DSS Level 1 certification to process card payments?+
No. By implementing client-side tokenization (Razorpay Checkout or Stripe Elements), cardholder data never touches your application server. This keeps your architecture compliant with PCI-DSS SAQ-A standards, eliminating expensive audits while maintaining maximum security.
Start a Project with Direct Technical Ownership
Tell me what you are building, what is currently blocked, and what outcome you need. I will review the brief and suggest the right next step: discovery, architecture, a fixed-scope build, or a technical audit.
📞 Calls Mon–Sat, 9:30 AM–7:30 PM IST · WhatsApp messages welcome anytime
Let's Build Your Custom Web Application
Whether you need a full-stack web app, a Node.js REST API, a Next.js SaaS MVP, an admin dashboard, or performance optimization for an existing application — I am available for freelance projects in Kerala, India, and worldwide.