Core Platform Engineer

Summary

Join KOMOJU, a leading cross-border payment gateway in Japan, and become part of a small, high-trust team focused on building and maintaining core backend systems and internal tools. You will work with engineers in a flat and inclusive culture, contributing to key product and technology decisions. The role involves a mix of greenfield development and infrastructure stewardship, utilizing Rust and Ruby on Rails. You will design, build, and maintain systems, develop and support organizational components, and take ownership of legacy components. The ideal candidate possesses strong communication skills, a solid understanding of software architecture, and practical experience with observability practices.

Requirements

• Production experience with Rust
• Strong communication skills—able to clearly document technical decisions and collaborate effectively across teams, including product engineering and SRE
• Strong grasp of software architecture, design patterns, and maintainability best practices
• Practical experience with observability practices, including structured logging, metrics, and distributed tracing
• Solid understanding of database performance characteristics, including indexing, query patterns, and caching strategies
• Familiarity with common web security risks and mitigation strategies (e.g., injection, CSRF, access control)

Responsibilities

• Design, build and maintain systems and internal tools using Rust and Ruby on Rails
• Develop and support components used across the organization, such as CI pipelines, observability tooling, and shared libraries
• Take ownership of under-maintained or legacy components, bringing clarity, stability, and improvement to critical but overlooked parts of the system, including occasional frontend or cloud infrastructure work
• Provide thoughtful feedback through code reviews and architecture discussions
• Identify and prioritize high-leverage opportunities that improve team velocity, system clarity, security, performance, and long-term maintainability
• Champion quality and reliability through automated testing, proactive monitoring, and iterative improvement of production systems

Preferred Qualifications

• Experience with any of: Ruby/Rails, JavaScript or TypeScript, Vue.js, React, Terraform, AWS, or observability tools like Datadog and OpenTelemetry
• Familiarity with payment systems, payment flows, or financial infrastructure
• Japanese language ability (reading or conversation)

Benefits

• At Degica, we embrace remote work while also offering office space for those who prefer in-person collaboration
• 10 days regular vacation, additional 5 days summer and 5 days winter vacation
• Paid birthday holiday
• Budget for self-learning allowance, to ensure our employees’ skills remain current
• Language training for Japanese