BackEnd Java Developer

Backend (Java) Developer
Experience Level : 5+ Years
Japan time zone

The Senior Backend Developer will take full ownership of driving development,
maintenance, and operational excellence. This role requires deep expertise in
Java/Spring Boot microservices, Kafka integration, MySQL, and Kubernetes-based
deployments. During the transition period, the Senior Backend Developer will be
responsible for understanding, documenting, and taking ownership of existing
business logic across the service portfolio, including complex integrations with BSS,
ASM, ATG, FCM, and other external systems.

Personal Characteristics

Strong portfolio and excellent attitude.
Must be self-confident to work in a Team and to handle
the responsibilities individually as well
Should be a good listener/ Can articulate well / Good
Communication Skills
Ability to work with teams across organizational
boundaries, different cultures and different time zones in
a virtual environment
Delivery oriented and able to work under strict
deadlines.
Strong portfolio and excellent attitude.
Must be self-confident to work in a Team and to
handle the responsibilities individually as well
Should be a good listener/ Can articulate well /
Good Communication Skills
Ability to work with teams across organizational
boundaries, different cultures and different time
zones in a virtual environment
Delivery oriented and able to work under strict
deadlines.

Take full ownership of 2 to 3 assigned microservices from the
following list: App/Main Controller, ASM Controller, BSS
Controller, Misc/Data Controller, Push Notification Controller, Email
Notification Controller, Scheduler, and Exporter.
Understand, document, and improve existing business logic
implemented across all microservices
Design, develop, and maintain scalable and high-performance
REST APIs consumed by the Frontend team and external systems
Implement Kafka producers and consumers for Push Notification
and Email Notification pipelines
Integrate with external systems including BSS, ASM, ATG, JID/RID,
FCM/Firebase, Email System, and Vault
Write clean, maintainable, and well-tested code following coding
standards and architectural guidelines
Conduct code reviews and provide constructive technical
feedback to team members
Write and maintain unit tests, integration tests, and regression test
suites
Maintain and improve Helm charts and Kubernetes deployment
configurations for owned services
Support L3/L4 escalations for production incidents related to
owned microservices
Contribute to MOP, test cases, test strategy, and technical
documentation
Participate in architecture reviews and contribute to technical
decision-making
Mentor junior developers and support knowledge sharing within
the team.

Bachelor's or Master's degree in Computer Science, Engineering, or a
related field
5+ years of professional backend software development experience
Expert-level proficiency in Java and Spring Boot for microservices
development
Strong experience with Apache Kafka including producer and
consumer implementation, topic management, and consumer group
handling
Solid experience with MySQL including complex queries, transactions,
indexing, and performance optimization
Hands-on experience with Docker and Kubernetes including pod
management, ConfigMaps, Secrets, and resource limits
Strong experience designing and consuming REST APIs including
OpenAPI and Swagger documentation
Experience with JWT, OAuth2, and token-based authentication and
authorization patterns
Experience integrating with Firebase/FCM for push notification delivery
Proficiency with Git and feature branch workflows
Experience with CI/CD pipelines using Jenkins, GitLab CI, or ArgoCD
Experience with Helm chart development and management
Strong understanding of Agile and Scrum development methodology.

Experience with Spring Cloud, Spring Batch, or Spring Scheduler for job
and scheduler implementation
Experience with HashiCorp Vault for secrets and certificate
management in application code
Familiarity with Strimzi Operator and Kafka on Kubernetes
Experience with Prometheus metrics exposition using Micrometer and
Grafana dashboards
Experience with distributed tracing tools such as Jaeger or Zipkin
Knowledge of Telecom domain including BSS/OSS provisioning
workflows and parent-child account management
Experience with log management tools such as ELK Stack or Loki
Experience with APM tools such as New Relic, Dynatrace, or Datadog
Familiarity with service mesh technologies such as Istio or Envoy
Experience with automated testing frameworks such as JUnit 5,
Mockito, and Testcontainers
CKAD (Certified Kubernetes Application Developer) certification