Nadir Husaain

Software Engineering

PLYAZ • Temps plein

Sep 2025 - Present • 1 yr 2 mos

I build payment systems that are secure, reliable, and built to handle real money. I’m a senior TypeScript/Node.js engineer specialising in payment infrastructure, billing, and financial systems. I designed and built a complete provider-agnostic payments SDK from scratch — around 13,000 lines across 88 TypeScript modules with 28 test suites. My experience includes: • Payment gateways with provider abstraction, routing, adapters, and fallback support • Stripe integrations, payment intents, refunds, saved payment methods, and checkout flows • Secure webhooks with HMAC verification, replay protection, idempotency, and event normalization • Database-level idempotency and transactional money operations to prevent duplicate charges • Double-entry ledgers, wallets, balance tracking, payment holds, adjustments, and audit trails • Subscription billing, upgrades, downgrades, proration, discounts, renewals, retries, and dunning • VAT/GST and sales-tax systems with jurisdiction-based rules, tax assessments, liabilities, refunds, and reporting • Multi-currency payments with FX conversion and exchange-rate tracking • KYC/payment limits, row-level security, GDPR-aware retention, and PCI-conscious architecture • Referral commissions, creator payouts, instalments, credits, and digital-asset trading flows I work primarily with TypeScript, Node.js, NestJS, Next.js, React, PostgreSQL, Redis, Supabase, Stripe, and Vitest. I don’t just connect Stripe and call it done. I focus on the difficult parts: retries, duplicate webhooks, refunds, reconciliation, billing edge cases, and keeping financial data consistent. Whether you need a payment system built from scratch, an existing integration fixed, or your payment architecture audited, I can help you build it correctly and make it ready to scale.

Software Engineering

DevNodes • Temps plein

Jun 2023 - Sep 2025 • 2 yrs 3 mos

I’m a full-stack TypeScript/Node.js engineer focused on building scalable, production-ready web and mobile applications. My experience includes designing a Google Drive-style Media Asset Management system for uploading, organizing, deleting, and reusing media across applications; building software release and build management workflows for versioning, publishing, and deployment tracking; and implementing real-time chat systems that enable customers and service providers to communicate instantly with persistent history and live notifications. I’ve also developed advanced multi-tenant theme customization, allowing service providers to configure colors, layouts, and visual modes based on their brand and service type. For the Trek Train platform, I designed core train search, scheduling, and seat-reservation systems with conflict prevention and scalable booking workflows. I also built a complete onboarding and authentication experience supporting phone, email, and Google sign-in, secure OTP verification, Terms & Conditions, dynamic registration flows, and location-based city selection. My focus is not just writing code—I build reliable systems with clean architecture, strong backend logic, intuitive user experiences, and scalability in mind.