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

Rakuten · Tokyo, Japan

Weak hiring record · median 263 days open

9292

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Actively hiring

Still listed on the employer's own board · How we score

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  • 80% of this employer's openings are over 60 days old

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  • Still listed on the employer's own board

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Backend Development Engineer -CPaaS Business Department (RS Product Delivery & Innovation Div) at Rakuten. We’ll keep it in your applied jobs, so you can see it later and be warned before applying to the same employer twice.

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)

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