Sr. Staff Back-end Engineer (Coupang Pay)
Coupang · Seoul
The fintech business of Coupang is reimagining financial services for both our consumers and sellers, so they can do more with their money.
Coupang Pay focuses on delivering innovative payment and financial services solutions to everyone who uses the Coupang app — from customers buying products on Coupang.com, to marketplace vendors, and restaurants that offer their services via Coupang Eats. We develop solutions with our latest tech innovations to serve the growing needs of Coupang’s customers in Korea and Taiwan. This includes Coupay, an online wallet with a proprietary one-touch payment capability.
In particular, we are rapidly scaling the Wow credit card, a co-branded card that offers industry-leading rewards as part of our efforts to maximize customer values. For sellers, we are building out multiple liquidity options to help small and medium sized enterprises grow their business, using BaaS (Banking as a Service) capability.
If you want to leverage your extensive experience within the fintech space, join us. We help customers spend less time checking out so they can spend more time shopping for what they love.
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 serving millions of customers at global scale.
- Work in an inclusive, high-impact culture that values innovation, speed, and craftsmanship.
- Competitive compensation, equity, benefits, and continuous learning opportunities.
Recruitment Process and Others:
Recruitment Process
- Application Review - 1st Interview - Virtual Onsite Interviews - Offer
- The exact nature of the recruitment process may vary according to the specific job and may be changed due to scheduling or other circumstances.
- Interview schedules and the results will be informed to the applicant via the e-mail address submitted at the application stage.
Things to Consider
- This job posting may be closed prior to the stated end date for application if all openings are filled.
- Coupang has the right to rescind an offer of employment if a candidate is found to have submitted false information as part of the application process.
- Coupang does not discriminate against disabled applicants or those with veteran status. We are proud to offer equal opportunities for all applicants.
- https://www.coupang.jobs/en/privacy-policy/
Document Return Policy
- This notification is given pursuant to Article 11 (6) of the Fair Hiring Procedure Act.
- A job applicant, who has applied but not been finally selected for a position at Coupang (the “ Company ”), may request the Company to return his/her hiring documents submitted pursuant to the Fair Hiring Procedure Act. However, this will not apply where the hiring documents were submitted via the website of the Company or e-mail, or where the job applicant submitted those documents voluntarily without a request from the Company. In addition, if the hiring documents were destroyed due to a natural disaster or any other reasons not attributable to the Company, such documents will be deemed to have been returned to the job applicant.
- A job applicant who wishes to request the return of his/her hiring documents pursuant to the main sentence of paragraph 2 above should fill out a “Request for Return of Hiring Documents” [Annex Form No. 3 in the Enforcement Rule of the Fair Hiring Procedure Act] and submit the request to the Company by email (recruitingops@coupang.com) In such case, within fourteen (14) days from the date of identifying the receipt of the request, the Company will send the hiring documents to the job applicant’s designated address via registered mail. Please be informed that the job applicant is required to pay the postage on the registered mail.
- In preparation for a job applicant’s request for the return of hiring documents pursuant to the main sentence of paragraph 2 above, the Company shall retain the original hiring documents submitted by the job applicant for 180 days from the completion of the recruiting process. If no request is made until the end of this period, all of his/her hiring documents will be destroyed immediately in accordance with the Personal Information Protection Act.
Equal Opportunities for All
Coupang is an equal opportunity employer. Our unprecedented success could not be possible without the valuable inputs of our globally diverse team.