Senior Fullstack Engineer

The Senior Fullstack Engineer is responsible for designing, developing, and integrating scalable software solutions across backend, frontend, and real-time systems. This is a hands-on

engineering role focused on system architecture, high-quality development, technical problem-solving, and end-to-end delivery.

Key Responsibilities

• Mentor the development members.
• Design and maintain overall system architecture.
• Develop and maintain backend services using Golang and C/C#.
• Develop web applications using modern frontend technologies.
• Design and implement real-time streaming and WebSocket solutions.
• Design and develop integrations with external systems, APIs, and third-party platforms.
• Support PoC, deployment, troubleshooting, and production issues.
• Perform code review and ensure development quality.
• Collaborate with Product, QA, and other teams to deliver projects successfully. Make technical decisions and drive solutions from requirement development integration deployment- production.

Your skills and experience

Must Have

• At least 5 years of experience in software development.

• Strong experience with Golang.

• Strong knowledge of System Architecture / System Design.

• Hands-on experience with Streaming / Real-time systems.

• Strong experience with WebSocket.

• Experience with Fullstack Web Development.

• Experience with C/C#.

• Proven experience in system integration / API integration / third-party integration.

• Experience with AWS, Docker, Kubernetes, and CI/CD.

• Experience leading or mentoring a software development team.

• Good ability to analyze requirements and translate them into technical solutions.

• Strong problem-solving and troubleshooting skills.

  Working Environment & Soft Skills

• Proactive, responsible, and able to work independently.

• Comfortable working in a fast-paced environment with changing requirements.

• Strong ownership of technical tasks and project delivery.

• Able to work effectively with developers, Product, QA, and other stakeholders.

• Good communication and teamwork skills.

• Able to balance technical quality, project timeline, and business requirements.

Nice to Have

• Experience working directly with customers, partners, or external technical teams.
• Good customer-facing and technical communication skills.
• Good communication skills in English, especially for technical discussions.
• Knowledge of V oIP / SIP / RTP / PBX / Contact Center.
• Experience with WebRTC or other real-time communication technologies.
• Good understanding of TCP/IP, HTTP/HTTPS, TLS, and networking.
• Experience with message queues / event streaming such as Kafka or RabbitMQ.
• Experience with databases such as PostgreSQL
• Experience with monitoring and observability tools.
• Experience working with international customers or distributed teams.

Why you'll love working here

Benefits

• Competitive salary.
• Comprehensive social insurance package and premium health insurance.
• Annual performance review with promotion opportunities.
• Five-day workweek (Monday–Friday).
• Opportunity to work on cutting-edge AI technologies with talented engineers.
• International career development opportunities in Japan, the United States, and other
• global markets.
• A dynamic and collaborative working environment with exciting employee activities,
• including annual Company Trips, YEP, team building events, and sports activities.