Senior Full-Stack Developer - Payment Gateway

We are building a **multi-vendor e-commerce platform** and are looking for an experienced developer to implement and improve our **enterprise-level payment gateway integration**. ### 💻 Tech Stack * NestJS Microservices * PostgreSQL * Cashfree Payment Gateway * Cashfree Easy Split * REST APIs & Webhooks ### 👨‍💻 Requirements * **5+ years of professional development experience** * **Mandatory payment gateway integration experience** * Experience with Cashfree / Razorpay / PayU / Stripe or similar * Strong knowledge of payment lifecycle, webhooks, refunds, settlements and reconciliation * Experience with NestJS, PostgreSQL and microservices * Strong understanding of idempotency, retries, failure handling and transaction consistency * Full-Stack development experience ### 🎯 Scope * Review existing payment integration * Implement enterprise-grade Cashfree integration * Secure payment and webhook flows * Webhook signature verification * Idempotency & duplicate-payment prevention * Payment success/failure/pending handling * Retry & fallback mechanisms * Refund & partial-refund flows * Cashfree Easy Split vendor flows * Settlement & reconciliation * Database consistency and audit logs * Testing and documentation * Production-ready implementation ### ⏱️ Timeline **Maximum: 5 days** Immediate availability preferred. ### 💰 Budget **Fixed Price: ₹100 — Negotiable** Price can be negotiated based on experience and expertise. ### 🤝 Long-Term This is intended to be a **long-term engagement** for continued development and maintenance of the platform. ### 🔐 Agreement Conditions * NDA / Confidentiality Agreement * IP Assignment Agreement * All source code and deliverables belong to the company * No reuse or redistribution of proprietary code * No sharing of source code, credentials or architecture * No unauthorized production access * No subcontracting without approval * Company Git repository must be used * Secure handling of credentials and sensitive data * Complete documentation and knowledge transfer * Full source-code handover required * Security vulnerabilities must be reported immediately ### 🧪 Apply With 1. Years of experience 2. Payment gateway experience 3. Cashfree experience 4. Easy Split experience 5. Relevant projects 6. NestJS/PostgreSQL experience 7. Availability to start 8. Confirmation of **5-day completion** 9. Negotiated price 10. Confirmation of interest in **long-term work** **Only candidates with genuine production payment-gateway experience should apply.**