Backend Developer (Ruby on Rails)

Working location: Tan My Ward, (District 7), HCMCSalary range: Up to VND 80,000,000 grossRESPONSIBILITIES●Design, build, and operate reliable backend services for payment products using Ruby andRuby on Rails.●Build and maintain APIs, services, and third-party integrations.●Implement payment flows across multiple currencies, countries, and payment methods.●Handle refunds, retries, idempotency, webhooks, asynchronous processing, and partialfailures.●Write clean, maintainable, and testable code; participate in code reviews and refactoring.●Improve system performance, reliability, observability, and security.●Investigate production issues, contribute to root-cause analysis, and prevent regressions.●Collaborate with product, QA, and other engineers; communicate risks early.REQUIREMENTS●3+ years of backend engineering experience for middle level, or 5+ years for senior level,including hands-on experience building applications with Ruby and Ruby on Rails.●English communication proficiency at B2 level or above.●Experience designing, building, and operating production APIs and backend services,including authentication and authorization, pagination, validation, and consistent errorhandling.●Practical experience troubleshooting production issues using application logs, metrics, stacktraces, and database queries.●Working knowledge of relational databases, preferably PostgreSQL or MySQL, includingschema design fundamentals, indexes, transactions, and writing SQL for investigation andtroubleshooting.●Experience working with background jobs and asynchronous workflows, including queues,retries, failure handling, and idempotency.●Experience debugging issues across APIs, background jobs, databases, and externalservice integrations.*** Nice to have●Payment or fintech experience.●Redis, Sidekiq, Kafka (or similar) experience.●AI-assisted coding/debugging tools (Claude Code/Copilot/Cursor) with strong reviewdiscipline.●Cloud infrastructure and containers.●PCI-aware development practices.