Sr. Staff Back-end Engineer (Coupang Pay)

About this role

Coupang Pay, a fintech subsidiary of Coupang Corp, provides payment gateway services for our growing and diverse business and customers. We focus on providing innovative payment and financial service solutions to all people and businesses that use Coupang’s platforms, ranging from the customers who make a purchase on coupang.com and use Coupang Eats service, the merchants who sell on Coupang’s open market platform, and the restaurants that use Coupang Eats delivery service. Coupang Pay strives to innovate all of our customers’ payment-related experiences with the team members who have the most diverse fintech experiences and have a good understanding of Coupang’s business.

Key Responsibilities

We are seeking a Sr. Staff Back-end Engineer who is both a visionary technical leader and a hands-on builder. This role combines architectural ownership, full-stack development, and distributed systems expertise to deliver payment systems with industry-leading scale, resiliency, and speed.

Hands-on Architecture & Development

• Architect, design, and implement complex, distributed, cloud-native systems spanning frontend, backend, APIs, data pipelines, and infrastructure.

• Write and review production-grade code; optimize critical paths for performance, reliability, and correctness.

• Lead by example in code quality, observability, CI/CD, and security.

Operate at Scale & Speed

• Deliver mission-critical features to millions of users with rapid iteration while maintaining high availability and data integrity.

• Optimize systems for concurrency, throughput, and cost efficiency under heavy global loads.

• Participate in on-call rotation and drive continuous improvements in reliability and incident prevention.

Full-Stack & Distributed Systems Leadership

• Own large-scale payment microservices, event-driven pipelines, caching systems, and real-time APIs.

• Guide teams across web/mobile frontends, middleware, and backend services to ensure cohesive and performant experiences.

• Spearhead adoption of best practices in distributed computing, fault tolerance, and multi-region scaling.

Innovation & Emerging Technology

• Drive adoption of AI/ML technologies—build or integrate AI agents and intelligent automations into payment workflows.

• Stay ahead of fintech innovation, evaluating and deploying new technologies to improve customer experience and system resilience.

Leadership & Mentorship

• Mentor senior engineers and Sr.Staff-level peers, fostering a culture of innovation, technical rigor, and rapid delivery.

• Collaborate cross-functionally with product, design, and infrastructure leaders to shape both technical vision and product strategy.

Basic Qualifications

• Bachelor’s degree in Computer Science, Software Engineering, or related field.

• 15+ years of software engineering experience, with proven success in large-scale distributed systems

• Deep expertise in full-stack development (Java, Go, Python, JavaScript/TypeScript, or equivalent) and core payment systems.

• Hands-on architecture and design experience with microservices, event-driven systems, APIs, and real-time data processing.

• Strong fundamentals in algorithms, data structures, concurrency, and system design.

• Proven ability to deliver rapidly and reliably in fast-paced, high-growth environments

Preferred Qualifications

• Master’s or PhD in Computer Science or related technical discipline.

• Payment systems experience at top global fintech companies (e.g., Stripe, PayPal, Razorpay, JusPay, AliPay, Visa, Adyen, Square, Mastercard).

• Hands-on experience building and deploying AI Agents (GenAI, RAG, workflow automation, LLMs) into production-scale systems.

• Deep knowledge of distributed microservices, cloud-native architectures (Kubernetes, containerization, serverless), and multi-region scaling.

• Experience in dealing with and resolving the issues that occur when an organization grows in size and the systems get complicated

• Publications, patents, or open-source contributions in distributed systems, payments, or AI applications.

• Fluent English (Korean a plus); strong communication skills with global stakeholders.

Why Coupang Pay?

• Shape the future of digital payments in one of the world’s fastest-growing e-commerce ecosystems.

• Own mission-critical systems…