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Backend Development Engineer CPaaS Business Department (RS Product Delivery & Innovation Div)

Rakuten


Job Location:

Tokyo - Japan

Monthly Salary: Not provided by the employer
Posted: 30 August 2026 (30+ days ago)
Application Deadline: 27 November 2026
Vacancies: 1 Vacancy

Job Summary

Job Description:

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)

Required Experience:

IC


About Company

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