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Backend Development Engineer -CPaaS Business Department (RS Product Delivery & Innovation Div)
Rakuten Symphony, Inc. · Tokyo, Japan
About The Role
About Organization
We are building the next generation of our CPaaS platform, a robust ecosystem powering multi-channel communication services. Our platform supports global traffic across SMS, Email, Voice, WhatsApp, LINE, RCS, Passkey, and advanced Authentication services. We are looking for a highly skilled Backend Engineer to drive the scalability, reliability, and evolution of these services within a high-autonomy, fast-paced R&D environment.
Job Duties
- Backend Service Development: Design, implement, and optimize microservices powering multi-channel communication workloads.
- Feature Engineering: Build and enhance backend capabilities supporting messaging, identity, verification, and communication APIs.
- Distributed Systems Engineering: Develop high-throughput, low-latency services for global CPaaS traffic.
- Database Engineering: Design schemas, optimize queries, and ensure peak performance across databases.
- Cloud-Native Architecture: Deploy and operate services on Kubernetes, ensuring resilience, scalability, and cost-efficiency.
- API-First Engineering: Build clean, scalable REST APIs and contribute to API-first product architecture.
- CI/CD & GitOps: Manage version-controlled pipelines for build validation, automated testing, and safe deployments.
- AI-Enhanced Development: Utilize LLM-based tools (e.g., Claude, Codex) to improve code quality, automate documentation, and accelerate development workflows.
- Observability: Ensure system visibility using Grafana, Prometheus, and structured logging.
- Cross-Functional Collaboration: Partner with Product Managers, QA, DevOps/SRE, and UI/UX teams to deliver high-quality features.
- Engineering Excellence: Uphold coding standards, conduct code reviews, and drive continuous improvement of engineering practices.
Minimum Qualifications
- 5+ years of hands-on backend development experience.
- Strong proficiency in Java or Golang.
- Expertise with Postgres and MySQL.
- Hands-on experience with Kubernetes and containerization.
- Experience with CI/CD pipelines (GitHub Actions preferred).
- Experience with Microservices and API-first system design.
- AI-Assisted Development: Proficient in leveraging LLM-based tools for coding, automation, and workflow acceleration.
- Advanced English proficiency (strong communication, documentation, and collaboration skills).
Preferred Qualifications
- Domain experience with communication protocols (SMPP, SIP, REST APIs, WebRTC).
- Experience across multiple CPaaS domains (SMS, Email, Voice, Passkey, Auth Services, WhatsApp, LINE, RCS, etc.).
- Proven ability to work effectively in fast-moving, high-autonomy environments.
Key Interfaces
- Backend Engineering Team
- QA & Automation Teams
- DevOps / SRE
- Product Managers
- UI/UX Designers
- Project Managers
- R&D Leadership / CTO
Languages
English (Overall - 3 - Advanced)
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