Job Description

Senior Full Stack Engineer (Backend-focused)

Company & Working Details

Company: Donuts Vietnam Co., Ltd.
Location: Binh Thanh District, Ho Chi Minh City, Vietnam
Working Model: Full-time, onsite
Working Hours: Flexible working hours (9:00–18:00, Monday–Friday)

Role Overview

We are looking for a Senior Full Stack Engineer to join our core development team and take ownership of features across our core product, with a strong emphasis on backend engineering, complex business rules, and external integrations.

You will work across backend and frontend development, application deployment, and server management, independently driving features from requirement clarification and technical design through production. You will contribute to architectural decisions, improve application performance and reliability, and help other engineers become more independent through code reviews, design feedback, and technical guidance.

You will work closely with the Technical Lead while taking substantial ownership of assigned features and technical areas.

Responsibilities

Independently deliver features across backend and frontend, from requirement clarification and design through testing, deployment, and maintenance.
Work with product and engineering teams to clarify business rules, identify edge cases, and communicate technical risks and trade-offs.
Design and implement complex business workflows, calculations, and validations, and contribute to backend architecture decisions.
Build reliable APIs and external integrations, ensuring data consistency and robust failure handling and retries.
Design database schemas, optimize queries, and resolve production issues, performance bottlenecks, and technical debt.
Deploy and operate applications, manage production servers, and improve CI/CD and application monitoring.
Improve automated testing and coding standards to maintain reliable, maintainable applications.
Review code and designs, and guide junior engineers toward greater independence.

Requirements

5+ years of professional software development experience preferred, or equivalent senior-level experience, with strong backend expertise in technologies such as Ruby, PHP, or Node.js.
Strong backend engineering fundamentals and willingness to work primarily with Ruby on Rails, learning the stack quickly if coming from another backend technology.
Practical frontend experience with HTML, CSS, JavaScript, React, and Redux.
Ability to clarify requirements, identify gaps, propose solutions, and independently deliver features through production.
Experience implementing complex business rules, workflows, validations, and edge cases.
Strong knowledge of software design principles, RESTful APIs, and web application security.
Experience with PostgreSQL or MySQL, including schema design, indexing, and query optimization.
Proficiency in automated testing, Git workflows, and code reviews, with a focus on maintainable code.
Hands-on experience deploying applications and managing Linux/Unix servers, including monitoring, performance tuning, and troubleshooting.
Strong problem-solving and communication skills, with the ability to collaborate across teams and provide technical guidance to junior engineers.

Nice to Have

Experience developing applications with Ruby on Rails.
Experience using AI tools in day-to-day software development and optimizing AI-assisted workflows, while validating outputs for correctness and code quality.
Experience in HR Tech, ERP, Accounting, Fintech, or other domains with complex operational rules.
Experience operating high-traffic or large-scale web applications.
Experience with cloud platforms such as AWS or GCP and infrastructure as code.
Experience with background processing tools such as Sidekiq or Shoryuken.
Hands-on experience with CI/CD tools such as GitHub Actions, CircleCI, or Jenkins.
Familiarity with monitoring and observability tools such as New Relic or Datadog.
Familiarity with Domain-Driven Design, modular architecture, and service boundaries.
Experience mentoring engineers or leading technical initiatives.

Compensation & Benefits

Annual performance and salary reviews.
13th-month salary.
Social, health, and unemployment insurance based on the full gross salary.
Annual health check-up.

Why Join Us

Meaningful product impact: Take ownership of features across our core product and build solutions that directly support business growth.
Challenging engineering work: Solve complex business logic and integration problems while improving application performance, reliability, and maintainability.
A focus on quality: Work with a team that values maintainable code, automated testing, and constructive code reviews.
Broad technical exposure: Work across backend and frontend development, database design, application deployment, server management, and CI/CD.
Autonomy and collaboration: Take ownership of your work and help shape technical direction through collaborative decisions.
Opportunities to support others: Share your experience, mentor teammates, and contribute to the team's engineering practices.

How to Apply

Please send your CV using the details below: