Senior Software Engineer

We are looking for a Senior Engineer to lead our transition from a reliable Ruby on Rails monolith to a modern, Service-Oriented Architecture. Company is at a "sweet spot" of growth: financially stable and profitable, yet small enough to maintain a flat structure where you work directly with founders. Your mission is not just to write code, but to challenge our assumptions, select our future tech stack, and evolve our system without disrupting a platform that handles high-traffic bookings and critical payment consistency. You will drive a "you build it, you run it" culture, emphasizing observability and architectural excellence. Key Responsibilities: Architectural Evolution: Lead the shift from monolith to SOA, defining domain boundaries and selecting a new tech stack (Go, Rust, Kotlin, etc.). Technical Leadership: Act as a domain leader, mentoring engineers and setting high standards for architectural design and code quality. Operational Excellence: Own the full software lifecycle, including CI/CD pipelines, zero-downtime deployments, and system observability. Product Partnership: Translate vague business requirements into concrete technical specs, identifying implicit needs like performance and security. Database Design: Build scalable schemas for high-reliability environments where payment integrity is paramount. Requirements Technical Breadth: Mastery of modern, statically-typed languages (e.g., Go, Kotlin, Rust, or C#) and concurrent programming. System Design: Proven experience building/maintaining services within an SOA and refactoring legacy monolithic codebases. Infrastructure/Ops: Hands-on experience with CI/CD (GitHub Actions/CircleCI) and scalable databases (Cassandra, AWS Aurora). Observability: Expertise in monitoring and alerting tools (Datadog, Grafana, or Prometheus). Communication: Exceptional English skills; ability to articulate complex concepts to non-technical stakeholders. Mindset: Proactive, entrepreneurial, and able to break down ill-defined problems into logical execution steps. Bonus: Proficiency in Japanese and/or experience with Ruby on Rails. Benefits Financial Stability: Join a profitable company with consistent growth and low churn. Flat Hierarchy: High agility with only one management layer between you and leadership. Comprehensive Coverage: Full social insurance (health, pension, employment, and workers' comp). Commuting: Allowance provided according to company regulations.

6-10 years