Senior Fullstack Engineer

Top 3 Reasons To Join Us

The Job

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.