About UPSIDER

UPSIDER is a Tokyo-based fintech company on a mission to build a global financial platform for challengers — the startups and fast-moving businesses driving Japan's next wave of economic growth.
We offer two core products: UPSIDER, a corporate card built for scale, and Shiharai.com, a business payment solution designed to simplify how companies manage spend.
Since launching, we have grown to serve over 100,000 companies across Japan, with cumulative transaction volume surpassing ¥1 trillion.
Backed by global investors including DST Global and Tencent, and operating as part of the Mizuho group, we combine the ambition of a startup with the credibility of one of Japan's leading financial institutions.

Our Platform Team

The Platform Team is responsible for delivering secure, reliable, and observable infrastructure that every engineer at the company depends on. We own the foundation — from release pipelines to cloud networking — so that product teams can move fast without breaking things.

We are a CNCF Silver Member and active followers of the Cloud Native ecosystem. While day-to-day priorities mean contribution time varies, we value engineers who engage with the community and look to create more space for that as we grow.

What You'll Work On

As a Platform Engineer, you will own and evolve key parts of our Cloud Native stack — including Kubernetes, Istio, the Grafana observability suite, ArgoCD, Terraform, and GCP-native services. You will research emerging technologies, make the case for adoption, and partner closely with development teams to support new and existing platform initiatives.

We think about our systems across two dimensions:

Pillars (technical ownership areas)

• Network — service mesh, ingress, DNS, connectivity
• Observability — metrics, logging, tracing, alerting
• Data Store — managed databases, caching, storage
• Environment Management — cluster lifecycle, provisioning, multi-tenancy
• Automation — CI/CD, GitOps, self-service tooling

Purpose (the lens we apply to every pillar)

• Security
• Reliability
• Cost Efficiency
• Developer Experience
• Open Source Contribution

You'll have room to develop a specialism, but the nature of platform work means you'll regularly cross all five pillars. Expect both depth and breadth.

• Japanese and English — Our team is distributed across Japan and Europe. Strong written and spoken proficiency in both languages is required for day-to-day collaboration and documentation.
• Kubernetes — Hands-on experience operating Kubernetes clusters in production (self-managed or managed service).
• GCP — Demonstrated experience operating workloads on Google Cloud Platform.
• Terraform — Infrastructure-as-Code experience with Terraform and strong GitOps practices.
• GitHub — Comfortable with GitHub-based workflows, including Actions, branch strategies, and pull-request-driven operations.
• Cloud Native fundamentals — Solid understanding of Cloud Native patterns: containerisation, service discovery, secrets management, and declarative configuration.
• Security awareness — Familiarity with information security fundamentals: secure development lifecycle, threat modeling, and security practices in public cloud environments.

• SRE experience — Background in site reliability engineering: SLOs, error budgets, incident management, and post-mortem culture.
• AWS — Experience with AWS as a secondary cloud provider.
• Platform tooling:
  • ArgoCD or another GitOps continuous delivery tool
  • Istio or another service mesh
  • Grafana, Prometheus, Loki, or Tempo for observability
• Datastore operations — Experience managing databases, caches, or object storage in cloud or on-prem environments.
• Networking — Experience with on-premises or cloud networking: VPNs, firewalls, load balancers, BGP.
• Coding skills — Go, Python, or Bash for automation, tooling, and glue code.
• PCI-DSS — Familiarity with operating regulated workloads under PCI-DSS.
• Open-source contributions — Prior contributions to open-source projects, technical or community.

This role suits engineers who are grounded in data, comfortable with ambiguity, and genuinely curious about how systems fail. You'll write documentation, present ideas to peers, and sometimes build the thing nobody asked for yet — but everyone ends up needing.

If you care deeply about the experience of the engineers around you, enjoy cross-functional collaboration, and want your work to directly shape how a company builds and ships software, this team is a strong fit.