Fullstack Developer – Transform Legacy Code into Scalable Excellence

Location: Fully Remote Full-time | 

Level: Senior

🚀 About the Role

We’re looking for a Fullstack Developer to fix, clean, and improve our system – two profitable SaaS products generating used by 8,000+ creators worldwide.

This isn’t about building from scratch. If you want greenfield projects, this isn’t for you.

If you love turning messy code into something scalable and maintainable while building features that impact thousands of users daily, keep reading.

💻 What You’ll Do

🔧 Code Quality & Performance

• Refactor and optimize our TypeScript/Next.js codebase for better performance and maintainability
• Identify and fix bugs across frontend and backend systems
• Improve code architecture to support rapid feature development
• Optimize database queries and API performance for high-traffic scenarios

🚀 Feature Development

• Build new features that enhance user experience and drive growth
• Integrate with social media APIs (Twitter Enterprise, LinkedIn) for new functionality
• Implement AI-powered features for content generation and optimization
• Create responsive UI components that work seamlessly across devices

🔍 Technical Leadership

• Challenge product requests with technical expertise and suggest better solutions
• Balance speed vs quality in feature delivery decisions
• Mentor junior developers and contribute to engineering best practices
• Participate in technical planning and architecture discussions

🛠️ Operations & Support

• Support customer success by resolving technical issues and performance bottlenecks
• Monitor application performance and proactively address issues
• Collaborate with DevOps on deployment and infrastructure improvements

🎯 Tech Stack

Frontend:

• TypeScript, React, Next.js
• Tailwind CSS, Styled Components
• State Management (Redux/Zustand)

Backend:

• Node.js, Express/Fastify
• TypeScript for type safety
• RESTful APIs & GraphQL

Database & Storage:

• PostgreSQL, Redis
• MongoDB for analytics data
• Cloud storage (AWS S3)

Infrastructure:

• Google Cloud Platform (GCP)
• Docker, Kubernetes
• CI/CD pipelines

APIs & Integrations:

• Twitter Enterprise API
• LinkedIn APIs
• Stripe, SendGrid
• Various AI/ML services

✅ What We’re Looking For

Must-Haves:

• English proficiency for technical communication and documentation
• 5+ years of fullstack development experience with modern JavaScript/TypeScript
• Proven track record of refactoring and optimizing legacy codebases
• Strong problem-solving skills with ability to debug complex issues
• Experience with React/Next.js and Node.js ecosystems
• Database optimization experience (PostgreSQL preferred)
• API integration experience and understanding of rate limiting, authentication
• Ownership mentality – you take responsibility for your code and its impact

Nice-to-Haves:

• Social media platform experience (Twitter, LinkedIn APIs)
• Google Cloud Platform (GCP) knowledge and deployment experience
• High-traffic application experience (10K+ concurrent users)
• AI/ML integration experience for content generation
• Performance optimization experience for web applications
• Open source contributions or technical blog writing
• B2B SaaS experience with subscription models

Personality & Work Style:

• Detail-oriented with passion for clean, maintainable code
• Proactive problem solver who identifies issues before they become critical
• Fast learner who can quickly understand existing codebases
• Team player who enjoys collaboration and knowledge sharing
• User-focused with understanding of how technical decisions impact UX

🎁 What’s in It for You?

💰 Compensation & Benefits

• Competitive salary: 55,000,000 VND ( NET ) / month + performance bonus 
• 100% remote work with flexible hours

🚀 Application Process

1. Initial Screening (30 min)

• Technical background discussion
• Motivation and culture fit assessment

2. Technical Interview (60 min)

• Live coding session focusing on refactoring existing code
• System design discussion for social media applications
• Debugging and optimization scenarios

3. Final Interview (45 min)

• Meet with engineering leadership
• Discuss technical vision and growth opportunities
• Q&A about role, team, and company

Candidates can apply by sending CV: contact@wiszy.vn

Phone/ Zalo: 077 450 8034

Title: [CV] Fullstack Developer – Transform Legacy Code into Scalable Excellence