Fullstack Lead Engineer (Tokyo)
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Overview
Mico provides Mico Engage AI, a high-traffic enterprise SaaS used daily by major companies, and we are currently hiring core members to join our team. In our fast-growing startup environment, you will have the opportunity to directly shape the product and elevate the user experience.
You will be expected to proactively tackle a wide range of challenges—including optimizing high-traffic systems, designing and developing new AI-powered features, and improving our real-time processing infrastructure. Working closely with our Lead Engineer, you will drive product-critical development while also contributing to technical decision-making and standardization.
By collaborating in a multicultural, bilingual team, you will sharpen your skills in a global development environment. This role offers far more than pure development—you will play a key part in the growth of both the team and the product, making it a highly rewarding position.
What You Will Gain
Experience building scalable systems and implementing AI technologies
Collaboration skills in a global engineering team
Hands-on experience driving product growth end-to-end
Tech Stack
Web Backend: TypeScript (NestJS), Go, Elixir
Web Frontend: TypeScript (Next.js), Chakra UI
Databases: TiDB, Aurora MySQL, DynamoDB, MemoryDB for Redis
Infrastructure: AWS (Cognito, EC2, ECS, Route53, Lambda, Kinesis, SQS, SES, RDS, API Gateway), IaC (Terraform, AWS CDK)
Monitoring & Analytics: New Relic, Sentry, CloudWatch, BigQuery, Metabase
CI/CD & Tools: Docker, GitHub Actions, Amplify, Slack, Notion, Jira
Responsibilities
- Stabilizing the Mico Engage AI delivery infrastructure: Build and improve the infrastructure that enables stable, large-scale delivery even for clients with high user volumes.
- Developing new features: Implement product-enhancing features based on our product roadmap.
- Customer-driven development: Build high-impact, reusable features based on needs identified through Customer Success activities.
Required Skills
- 5+ years of hands-on experience in system development
- Experience developing with TypeScript and React
- Full-stack engineering experience (both frontend and backend)
- Ability to independently handle the full development cycle from requirements definition to release
- 2+ years of code review experience
- Ability to write test code and contribute to improving product quality
- Experience in technical decision-making (evaluating technical requirements, cost, and maintainability)
- 2+ years of experience leading development as a technical lead (teams of 5+ members)
- Experience designing REST APIs
- Business-level proficiency in Japanese
Preferred Skills
- Experience developing with Go or Next.js
- Experience designing systems using Domain-Driven Design or Clean Architecture
- Experience developing gRPC APIs
- Ability to effectively leverage AI to improve development speed and quality
- Experience in infrastructure setup (AWS, Docker, etc.)
- Business-level proficiency in English
Hiring Process
Document Screening + Coding Test
Casual Interview (Japanese Language Check)
First Interview
Second Interview
Third Interview
Final Interview + Reference Checks
Job Offer Meeting
Quick Facts
Submit your application for this role at Mico.