• Design, develop, and maintain the Transactional Billing Automation platform, including tracking contract information, prepaid usage blocks, rollovers, and calculating projected usage and balances. • Build and support responsive web application and RESTful APIs to automate transactional billing operations and reduce manual processing. • Develop dynamic UI components for managing customer contracts, multi-product selections, invoice details, and billing summaries. • Implement business logic for prepaid balances, rollover amounts, block total calculations, invoice validations, and contract lifecycle management. • Collaborate with product owners, software engineers, and QA engineers to gather billing requirements and deliver scalable automation solutions. • Create reusable components, clean architecture patterns, and well-documented APIs to improve maintainability and long-term scalability. • Develop unit tests, integration tests, and automated validation processes to ensure billing accuracy and support safe application enhancements. • Participate in code reviews and enforced coding standards, security best practices, and performance optimization techniques. • Develop operational dashboards and billing reports to provide visibility into contracts, prepaid usage, rollover balances, projected customer usage, and actual consumption trends. • Follow development standards, branching strategies, and pull request workflows to deliver clean, secure, and maintainable code through reviews and testing. • Support Agile development processes, including sprint planning, backlog refinement, stand-ups, demos, and retrospectives.

Role Description The Backend Engineer is responsible for the system to work behind the scenes. The role is to integrate the application with all required systems and services and provide clean and easy-to-use API for the frontend part of the system. Although the work is usually hidden from the user, the Backend Engineer bears the full responsibility for the application functionality, performance and scalability. - Design and develop the business logic and backend systems of the product - Work closely with frontend developers to design and develop functional, performing and complete APIs - Decipher existing companies software systems and be able to hook in application to applicable data sources - Write both unit and integration tests, and develop automation tools for daily tasks - Develop high quality, well documented, and efficient code - Challenge ideas and opinions to avoid pitfalls and inefficient solutions Qualifications - You have experience as a backend engineer in common languages and frameworks, e.g., Java, Node Js, ExpressJS, NestJS or any other JS framework - You have experience in AWS - You have experience in GraphQL - You have deep knowledge of object-oriented programming and engineering principles such as SOLID - You have significant experience writing and utilizing autonomous services-oriented restful API services and performance tuning large scale apps - You have experience with database systems, with knowledge of SQL and NoSQL stores, e.g., MySQL, MongoDB, Redis, Postgres - You are able to write effective unit, integration, and API tests. It is a plus if you experience integrating with JavaScript frameworks, such as React Benefits - Full social insurance and housing fund - Year-end bonus - Phone allowance - Transportation allowance - Best Culture - Clear focus. - Diverse Workplace (Our members are from around the world!) - Non-hierarchical and agile environment - Growth opportunity and career path

• Responsible for developing the platform backend, focusing on billing, subscriptions, checkout, dependents, profiles, authentication, integrations and transactional rules. • Develop Java backend APIs and services for the plans, offers, checkout, subscription, billing, dependents and authenticated-user areas. • Implement integrations with payment gateways, financial webhooks, recurring billing, retry logic, delinquency handling and subscription cancellations. • Build business rules for subscription status, benefit blocking, payment history, eligibility and hierarchical scope. • Implement authentication, first-time access, profile-based authorization and permission control by partner, company and beneficiary. • Develop integration components with NAV, notification services, caching, auditing and other required systems. • Apply best practices for unit testing, error handling, logging, API versioning and technical documentation.

• Develop applications using object-oriented Java; • Apply Design Patterns and development best practices; • Develop and maintain APIs and REST services; • Work with distributed architectures and microservices; • Develop using Spring Boot and Spring Cloud; • Implement and maintain integrations with Kafka; • Work in Kubernetes environments; • Write unit tests; • Participate in code reviews; • Collaborate on architecture definition and development best practices.