Senior Software Engineer, Autonomous Cloud Network - Mercari

Location: Minato City, Tokyo, Japan
Employment Status: Full-time
Work Hours: Full Flextime (no core time)
Office: Roppongi
Remote/Hybrid: Hybrid

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Description

Our team's mission is to make the communication between our customers and our systems smooth, reliable, and secure.

The network is the critical bridge that connects users to Mercari's applications and the systems behind them. These systems are complex, widely distributed, and composed of diverse data paths.

The Networking Platform team helps Mercari engineers deliver more reliable services and improve development efficiency by providing network infrastructure and DevOps support. We manage the entire network, from edge areas such as the CDN to the cloud, service mesh (Istio), and physical data centers.

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Work Responsibilities

• Design, develop, and evolve the cloud networking and infrastructure that supports the entire business
• Design and implement networking/infrastructure solutions that support our global and multi-region strategy
• Improve systems to reduce operational engineering cost
• Support the migration and adoption of new platform features and tools
• Improve and drive security and reliability in collaboration with the SRE and Security teams
• Automate day-to-day platform operations to improve efficiency and reduce toil
• Collaborate with internal developers to understand their needs and deliver solutions

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Unique Challenges

In this position we are looking for a software engineer with knowledge of, or interest in, developing platform network and infrastructure systems, with hands-on DevOps and coding experience. The ideal person is passionate, proactive, and able to see an imperfect system as an opportunity rather than a problem. This role suits someone who enjoys rolling up their sleeves to shape the environment and drive impactful improvements, who can identify and solve problems on their own, and who can steadily add features to large-scale systems.

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Qualifications

Required Experience/Skills

• Strong networking fundamentals (TCP/IP, IP address management, OSI layers 4–7, cloud routing, CDN, DNS, TLS, HTTP)
• Production experience building and operating cloud networks using GCP or AWS
• Production experience building and operating Linux and Kubernetes networking
• Knowledge of network proxies (Envoy, HAProxy, Nginx) and regional/VPC routing
• Production experience operating CDNs (e.g., edge/cache configuration, multi-CDN, performance and security)
• Production experience with a service mesh such as Istio (e.g., traffic management, reliability practices)
• Ability to automate network-related workflows using any familiar language (Go, Python or Bash etc) and to deliver capabilities as a service
• Experience managing network configuration using Infrastructure as Code (IaC)
• Experience writing design documents, collaborating with stakeholders, and making technical decisions
• A track record of developing tools for internal users and improving platform operations
• On-call and production troubleshooting experience for reliability-critical systems (incident response, debugging, and root cause analysis)
• Empathy with Mercari's mission and values

Preferred Experience/Skills

• Passion for delivering a pleasant user experience through the platform and supporting operational efficiency
• Experience building and operating networks in large-scale distributed systems composed of hundreds of microservices
• Production experience operating service meshes such as Istio or Linkerd
• Experience architecting scalable, highly available infrastructure or middleware (e.g., control planes, Kubernetes operators/CRDs, or service-as-a-platform APIs)
• Experience with agent-driven workflows and usage of agentic tools such as Claude, Cursor, and Codex
• Experience developing and maintaining CI/CD pipelines (e.g., GitHub Actions, Argo CD)

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Language

• English: Proficient (CEFR – C1)
• Japanese: optional, but preferred