Senior Fullstack Engineer (Mico Message)

**About the company:** Mico Minato-ku, Tokyo We offer multiple products that deliver conversational experiences, including MicoCloud, a platform that is used by over 1,000 clients to reach over 29 million people. **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 Compensation ¥7,000,000 ~ ¥9,000,000 annually. APPLY FOR THIS POSITION DO YOU NEED MORE INFO? ASK A QUESTION About Mico Mico Minato-ku, Tokyo We offer multiple products that deliver conversational experiences, including MicoCloud, a platform that is used by over 1,000 clients to reach over 29 million people. Key benefits A growing company in a growing market Open and inclusive communication Team over self Read more More jobs like this We'll send you a digest of new English-friendly software developer jobs in Japan. Your email stays private, we don't share or sell it. Apply for this position × This position is only open to current residents of Japan. This position requires conversational Japanese. I have a favour to ask. When you apply to Mico, please tell them that you heard about the position on TokyoDev . This helps to keep this job board sustainable, so I'd be grateful for your support with this. - Paul, Founder of TokyoDev Continue applying © 2026 Privacy Policy **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 have:** 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 **Compensation:** ¥7,000,000 ~ ¥9,000,000 annually. APPLY FOR THIS POSITION DO YOU NEED MORE INFO? ASK A QUESTION About Mico Mico Minato-ku, Tokyo We offer multiple products that deliver conversational experiences, including MicoCloud, a platform that is used by over 1,000 clients to reach over 29 million people. Key benefits A growing company in a growing market Open and inclusive communication Team over self Read more More jobs like this We'll send you a digest of new English-friendly software developer jobs in Japan. Your email stays private, we don't share or sell it. Apply for this position × This position is only open to current residents of Japan. This position requires conversational Japanese. I have a favour to ask. When you apply to Mico, please tell them that you heard about the position on TokyoDev . This helps to keep this job board sustainable, so I'd be grateful for your support with this. - Paul, Founder of TokyoDev Continue applying © 2026 Privacy Policy