Full Stack Engineer (Mico Engage AI) - Tokyo

At Mico, we provide Mico Engage AI, a high-traffic enterprise SaaS platform used daily by major corporations, and we are currently looking for core members to join our team. This is an exciting opportunity to refine a fast-growing product and enhance user experience in a dynamic startup environment.

You’ll take ownership of a wide range of challenges—such as optimizing large-scale, high-traffic systems, designing and developing AI-driven features, and improving real-time processing infrastructure. Working closely with the Lead Engineer, you will drive product growth while also contributing to key technical decisions and standardization efforts.

As part of a multicultural and bilingual team, you’ll use both Japanese and English in a truly global development environment, sharpening your skills across borders. This is a highly rewarding position where you can make a direct impact not only through development but also by contributing to the growth of both the product and the team.

Main Responsibilities

As a Full Stack Engineer, you will play a central role in the Mico Engage AI development team. Your responsibilities include:

• Stabilizing the Mico Engage AI delivery infrastructure — Building and maintaining infrastructure that ensures reliable performance for clients with large user bases.
• Developing new features — Implementing functionality based on the product roadmap to increase overall product value.
• Customer-driven development — Delivering high-demand, scalable features based on requests gathered through Customer Success activities.
• Continuous improvement — Addressing product backlog items, enhancing UI/UX, and promoting better Developer Experience (DX) by responding to customer feedback and internal needs.

Tech Stack

• Web Backend: TypeScript (NestJS), Go, Elixir
• Web Frontend: TypeScript (Next.js), Chakra UI
• Database: TiDB, Aurora MySQL, DynamoDB, MemoryDB for Redis, Snowflake
• Infrastructure: AWS (Cognito, EC2, ECS, Route53, Lambda, Kinesis Data Stream, Kinesis Firehose, SQS, SES, ElastiCache, RDS, CloudWatch, IAM, Audit, APIGateway, CodeDeploy), IaC (Terraform, AWS CDK)
• Middleware: Nginx, Supervisor
• Monitoring: NewRelic, Sentry, AWS CloudWatch
• Data Analytics: BigQuery, Google Data Studio, Google Analytics, Metabase, Trocco
• Environment Setup: Docker
• CI/CD: GitHub Actions, Amplify Hosting
• CDN: CloudFront
• Source Control: GitHub
• Communication Tools: Google Meet, Slack, Notion, Redmine, Jira, ClickUp

Required Skills

Experience

• 5+ years of hands-on experience in system development
• Ability to complete the entire development cycle independently, from specification design to release
• Proven ability to write clean, high-quality, and maintainable code
• Experience in writing test code to ensure and improve software quality
• Technical skills for proof-of-concept and prototyping

Technical Skills

• Ability to implement high-quality, maintainable code
• Capable of writing test code to enhance product quality
• Strong technical skills for verification and prototyping
• Ability to design and build comprehensive architectures that consider performance, scalability, security, operations, and cost for technical problem-solving
• Experience in designing, implementing, reviewing, and maintaining high-quality backend code using TypeScript, NestJS, and an ORM of choice
• Proficiency in developing efficient database operations (e.g., SQL) that balance load, performance, and flexibility
• Experience designing and implementing production-level frontend code and tests using TypeScript and React
• Experience designing REST APIs
• Business-level communication skills in both Japanese and English

Preferred Skills

Experience

• Experience in product management for web or mobile applications
• Experience working in a startup environment
• Experience interviewing and evaluating at least 5 candidates based on hiring requirements

Technical Skills

• Ability to design scalable code and architecture to handle large volumes of data and traffic
• Development experience using gRPC APIs
• Development experience in Go language
• Experience designing systems based on Domain-Driven Design (DDD) or Clean Architecture

Work Location

• Your preferred work location will be discussed.
  • Osaka Office : WeWork Midosuji Frontier 1-13-22 Sonezakishinchi, Kita-ku, Osaka-shi, Osaka Prefecture
  • Tokyo Office : WeWork The ARGYLE Aoyama 6F 2-14-4 Kita-Aoyama, Minato-ku, Tokyo
• Flexible work styles are available depending on job responsibilities (remote/on-site).
  • Average On-Site Frequency:About 4 days per month

Work Hours

• Standard Schedule: 9:00 AM – 6:00 PM (includes a 1-hour break; overtime applicable).
• Flexible Time: Core hours from 10:00 AM to 4:00 PM.
• Certain grades may fall under a discretionary labor system, per company regulations.

Holidays and Leave

• Weekends (Saturday & Sunday), national holidays
• Year-end and New Year holidays
• Summer vacation
• Bereavement leave
• Paid leave (10 days granted upon joining, with additional days based on tenure)
• Other company-designated holidays

Probationary Period

• Generally 3 months (no changes in compensation or benefits during this period).

Benefits

• Commuting allowance (including bicycle commuting)
• Company laptop provided
• Company phone provided (*role-specific)
• Flexible start-time policy (every two months upon request)
• Social insurance (health, pension, employment, workers' compensation)
• Life and health support leave
• Health checkup expenses covered
• Parental and childcare support programs
• Club activity support

Hiring Process

• Document Screening
• Casual Interview (Japanese Language Check)
• Cording Test
• First Interview
• Second Interview
• Reference Checks
• Final Interview
• Job Offer Meeting

*The hiring process is subject to change.