Backend Development Engineer

Job Description

 Appealing Points:

• Build and optimize high-throughput, low-latency distributed systems supporting global multi-channel communication workloads.
• Work with modern technologies including Java/Golang, Kubernetes, microservices, CI/CD, API-first architecture, and cloud-native systems.
• Leverage LLM-based AI development tools such as Claude and Codex to improve code quality, automate documentation, and accelerate development workflows.

Annual salary : 7 Million Yen and Above.

Job Responsibilities:.

• Design, implement, and optimize microservices for multi-channel communication workloads.
• Build and enhance backend capabilities supporting messaging, identity, verification, and communication APIs.
• Develop high-throughput, low-latency services for global CPaaS traffic.
• Design database schemas, optimize queries, and ensure database performance.
• Deploy and operate services on Kubernetes, ensuring resilience, scalability, and cost efficiency.
• Build scalable REST APIs and contribute to API-first product architecture.
• Manage version-controlled CI/CD pipelines for build validation, automated testing, and safe deployments.
• Use LLM-based tools such as Claude and Codex to improve code quality, automate documentation, and accelerate development workflows.
• Ensure system visibility using Grafana, Prometheus, and structured logging.
• Collaborate with Product Managers, QA, DevOps/SRE, and UI/UX teams to deliver high-quality features.
• Maintain coding standards, conduct code reviews, and continuously improve engineering practices.

Job 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, with GitHub Actions preferred.
• Experience with microservices and API-first system design.
• Proficiency in leveraging LLM-based tools for coding, automation, and workflow acceleration.
• Advanced English proficiency, including strong communication, documentation, and collaboration skills.

Preferred Qulifications:

• Domain experience with communication protocols such as SMPP, SIP, REST APIs, and WebRTC.
• Experience across multiple CPaaS domains including SMS, Email, Voice, Passkey, Authentication Services, WhatsApp, LINE, and RCS.
• Ability to work effectively in fast-moving, high-autonomy environments.

Language Requirements: Advanced level English - strong communication, documentation, and collaboration skills.

About Company:

The largest eCommerce company in Japan, and the third-largest eCommerce marketplace company worldwide. The organization provides a variety of consumer and business-focused services including e-commerce, e-reading, travel, banking, securities, credit card, e-money, portal and media, online marketing, and professional sports.  The company is expanding globally and currently has operations throughout Asia, Western Europe, and the Americas. 

[Measures against passive smoking]

No smoking indoors allowed

Designated smoking area