Senior Frontend Engineer Job at Optimizely (Hanoi)

Senior Frontend Engineer

Optimizely

Location:
Vietnam , Hanoi

Category:
IT - Software Development

Contract Type:
Not provided

Salary:

Not provided

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Job Description:

This role is part of the engineering team behind Optimizely Campaign, a large-scale customer engagement and messaging platform that enables global brands to design, automate, and deliver personalized cross-channel communications at scale. The team works on high-volume, real-time systems where reliability, performance, and data-driven experiences are critical. We are looking for a Senior Frontend Engineer to join the Campaign engineering team and help evolve the user interface of a complex enterprise SaaS product. In this role, you will play a key role in modernizing the frontend architecture, collaborating closely with Product, UX, and Backend teams, and delivering scalable, high-quality user experiences for international customers. This position is ideal for engineers who enjoy ownership, technical depth, and shaping the direction of large web applications.

Job Responsibility:

Collaborate with an agile, cross-functional team to develop new user-facing features and enhance existing ones, adhering to clean code principles and test-driven development
Work with the UI/UX designer and bridge the gap between UI design and technical implementation, take an active role on both sides and define how the application looks as well as how it works
Write reusable code and libraries for future use
Review pull requests from colleagues, offering constructive feedback
Contribute to the modernization of an existing monolithic frontend, including transitioning from a classical technology stack (e.g. JSP, jQuery) towards a modern, component-based and micro-frontend architecture
Collaborate closely with Product, UX/UI, and Backend engineers to implement customer-centric solutions
Take ownership of frontend features from design through implementation and iteration
Contribute to and follow test-driven development and frontend quality best practices
Leverage AI-assisted development tools to improve code quality, productivity, and experimentation

Requirements:

Strong general expertise in software engineering
At least 5 years of professional experience developing large-scale web applications using JavaScript, React, Typescript, HTML, CSS, and various persistence technologies
Fluent in English (verbal and written), and have good collaboration and communication skills
Understand the value of modern software engineering practices such as Agile, pair programming, TDD, and principles of clean code
Team player with a profound practical experience in implementing large web applications in an agile, cross-functional environment
Able of taking ownership of complex initiatives, and drive them even from the early phases when uncertainty and risks have to tackled
Always thinking about the end product and how to improve the experience for users
Like to contribute to team discussions on everything from ideation through architecture and design to implementation and support of the products and services
Experience configuring or maintaining CI/CD tools
Proactively anticipate, investigate and resolve problems
Know how to write semantic and accessible HTML, how to maintain CSS at scale, and are well-versed in JavaScript (including concepts like asynchronous programming, closures and prototypal inheritance)
Strive to write clean and well-tested code
Feel comfortable leveraging the type system in TypeScript or another statically-typed language
Proficient with React and enjoy crafting delightful and performant UIs
Used to working with design systems and implementing reusable components
Have experience consuming RESTful APIs
Demonstrate an AI-first mindset, using AI tools responsibly to support development, debugging, testing, and learning

Nice to have:

Ideally, you are also familiar with the Java programming language and can understand and navigate existing code
Nice if you also have prior exposure to Piral or similar micro-frontend frameworks

Additional Information:

Job Posted:
March 18, 2026

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