Senior Fullstack Engineer (Mico Message)

Mico Message is Mico’s AI-native customer engagement platform. Through messaging automation, real-time communication, and AI-powered interactions, we develop systems that build meaningful relationships between businesses and their customers.

As a Full Stack Lead Engineer , you will lead the design and development of both frontend and backend systems powering Mico Message. Beyond implementation, you will provide technical leadership across architecture design, engineering best practices, mentoring, and operational excellence.

Working closely with our Product, Design, AI, and Infrastructure teams, you will help deliver scalable and intuitive customer engagement experiences used by enterprise customers in Japan and across global markets.

What We Expect

We are looking for someone who can:

• Enjoy solving complex technical and product challenges while balancing speed and long-term maintainability
• Communicate effectively with both technical and non-technical stakeholders
• Work independently while collaborating in a distributed, remote-first environment
• Take meaningful ownership of system architecture and product direction
• Contribute proactively to engineering culture and technical standards

What You’ll Gain

• The opportunity to shape the future of AI-powered customer engagement
• Significant influence over architecture, engineering standards, and product direction
• High ownership and autonomy in decision-making
• A collaborative, global, remote-first engineering culture
• Continuous learning and professional growth opportunities
• Competitive compensation and benefits
• Flexible working arrangements built on trust and accountability

Career Opportunities

• Advance your expertise as an Engineering Lead toward roles such as Software Architect or Technical Lead
• Grow into Engineering Manager or CTO-track positions through involvement in both product and business strategy
• Play a key role within a global engineering organization

Responsibilities

• Lead the design and development of scalable frontend and backend systems for Mico Message
• Build and enhance customer-facing applications as well as internal operational tools
• Design robust APIs, backend services, and platform integrations
• Drive technical decision-making and contribute to system architecture discussions
• Collaborate closely with Product and Design teams to shape product direction and user experience
• Continuously improve system reliability, scalability, performance, and operational observability
• Develop well-tested, maintainable code following modern engineering best practices
• Establish and improve engineering standards, development workflows, and technical processes
• Mentor engineers through code reviews, technical guidance, and knowledge sharing
• Troubleshoot and resolve complex production issues in distributed systems
• Communicate effectively across cross-functional teams in both Japanese and English
• Take end-to-end ownership from requirements gathering through production deployment and ongoing operation

Requirements

• 5+ years of professional software engineering experience
• Experience working in Agile and Scrum development environments
• Business-level proficiency in both Japanese and English
• Strong full-stack web application development experience
• Experience with frontend technologies such as React, Vue.js, or Next.js
• Experience with backend technologies such as Node.js, Python, Elixir, Ruby, or PHP
• Experience designing scalable APIs and backend systems
• Deep understanding of software architecture, system design, and technical trade-offs
• Experience with relational databases such as PostgreSQL or MySQL
• Experience owning production systems in live environments
• Experience mentoring engineers and leading technical initiatives
• Excellent communication, debugging, collaboration, and problem-solving skills
• Ability to thrive in ambiguous environments and proactively drive projects forward

Nice to haves

While not specifically required, tell us if you have any of the following.

• Experience with statically typed languages, including TypeScript or Python type hints
• Experience using gRPC and Protocol Buffers
• Experience with Elixir/Phoenix or functional programming
• Experience building scalable SaaS platforms
• Understanding of conversational AI and LLM-powered applications
• Experience designing event-driven architectures and distributed systems
• Experience collaborating closely with Infrastructure or DevOps teams
• Experience improving engineering processes and development workflows
• Experience working in fast-growing startups
• Interest in AI-assisted software development workflows