Backend Developer (Ruby on Rails)

Working location: Tan My Ward, (District 7), HCMC

Salary range: Middle: Up to VND 45,000,000 gross; Senior: Up to VND 65,000,000 gross

RESPONSIBILITIES

• Design, build, and operate reliable backend services for payment products using Ruby and Ruby 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 partial failures. 
• 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 error handling. 
• Practical experience troubleshooting production issues using application logs, metrics, stack traces, and database queries. 
• Working knowledge of relational databases, preferably PostgreSQL or MySQL, including schema design fundamentals, indexes, transactions, and writing SQL for investigation and troubleshooting. 
• Experience working with background jobs and asynchronous workflows, including queues, retries, failure handling, and idempotency. 
• Experience debugging issues across APIs, background jobs, databases, and external service 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 review discipline. 
• Cloud infrastructure and containers. 
• PCI-aware development practices.