Senior Software Engineer, Platform

Senior Software Engineer

Welcome to Our World. We've been leading the charge in the affiliate industry from day one—establishing performance marketing and paving the way for future innovations. We're known for maintaining one of the largest, most reliable partnership platforms with impeccable, personalized service. Founded in Santa Barbara, California in 1998, CJ (formerly Commission Junction) stands as the most trusted name in performance marketing. We specialize in building partnerships between top brands and reputable publishers to drive revenue and business growth. CJ's industry-leading solutions make us the platform of choice for over 3,800 global brands across sectors like retail, travel, finance, technology, and home services. As part of Publicis Groupe, our savvy data capabilities, cutting-edge tech, and strategic expertise facilitate genuine connections, allowing brands to reach consumers wherever they are.

This is a hybrid role requiring 3 days a week. You must be work authorized in the United States without the need for employer sponsorship. Must have Ad Tech / MarTech industry experience, specifically in e-commerce, travel, and finance.

As a Senior Software Engineer on the Engineering Experience (EngExp) platform team, you help run and evolve the platform that powers CJ's production systems across multiple AWS regions. "Platform" here is broad - it is the Kubernetes clusters, but also the observability stack every squad depends on, the CI/CD and artifact infrastructure their builds run through, the AWS networking that connects them, the secrets and access systems that gate them, and the cost visibility that keeps them accountable. EngExp owns all of it, and this role touches most of it. This is not just an infrastructure role - your value is in engineering judgment. You are a leader on the team: you own the reliability and operability of the platform, act as a critical reviewer of systems and changes, set standards, and mentor other engineers. We especially want someone with real depth in the systems below - we have made platform decisions we later had to reverse because the team lacked deep expertise in a component we owned, and that depth is exactly what this role brings.

Responsibilities

The Systems You Work On:

You'll own their reliability, be the critical reviewer of changes to them, and raise the team's depth in them:

• Observability & monitoring — Prometheus, Alertmanager, Grafana, and OpenTelemetry across every production region. This is not dashboard-building: you own cardinality budgets and recording-rule design, keep a production Prometheus healthy as it outgrows a single shard (federation / sharding / long-term store strategy), and own Alertmanager HA and the blast radius of alert-routing config. Deep Prometheus and Alertmanager expertise is a core requirement.
• Kubernetes & cloud infrastructure — multi-region EKS clusters: upgrades, node group and Karpenter management, controller lifecycle, and add-on / configuration management. Identify failure modes before they happen (subnet IP exhaustion, API server latency, ArgoCD reconciliation lag, Prometheus cardinality, Karpenter consolidation disruption).
• AWS networking — VPC design, subnet allocation and CIDR management, VPC peering, Transit Gateway, security groups, Route53, and NAT gateway topology across multiple accounts and regions, plus 24/7 networking alarms for all prod networking between clusters and squad resources.
• CI/CD & artifact management — GitLab administration (runner fleet, AMI updates, cache, access - not just pipeline authoring), GitOps delivery through ArgoCD, and the Nexus artifact repository including its storage lifecycle as it grows.
• Access & identity — Vault secrets management, IAM roles and service accounts for apps in clusters, cluster permission management for audit compliance, and AI model access management (including cost alerts and reporting).
• Cost observability — OpenCost, EBS orphan cleanup, cost anomaly investigation, and rightsizing attribution across teams, so waste is attributable rather than shared overhead.
• Internal tools & delivery — the container image build pipeline and base image standards, code audit tooling, HedgeDoc, and the UI CDN (S3 + CloudFront), plus adopted applications with no other owner.

What You'll Do:

• Own the reliability and operability of the systems above - focused on what is happening and why
• Establish and enforce platform standards: RBAC, admission webhooks, resource limits, LimitRanges, policy-as-code
• Manage infrastructure-as-code with Terraform across AWS accounts
• Act as a high-quality reviewer of infrastructure changes - Terraform, Kubernetes configs, CI/CD pipelines, observability config - catching subtle issues and long-term risks before they ship
• Turn recurring requests (ingress, DNS, service accounts) into self-service workflows that are hard to misuse
• Drive resolution of platform incidents with a focus on learning and lasting system improvement
• Evaluate new patterns (Gateway API / Kgateway, claim-based self-service) on tradeoffs, not hype
• Mentor less-senior engineers and raise the team's depth in the components we own

Technologies We Use:

• Kubernetes / EKS (multi-cluster, multi-region), Karpenter, cert-manager, external-dns
• Prometheus, Alertmanager, Grafana, OpenTelemetry (and long-term storage / sharding for Prometheus)
• AWS networking (VPC, VPC peering, Transit Gateway, Route53, NAT Gateway, security groups, subnet/CIDR design across accounts and regions)
• Terraform, AWS (IAM, EKS, S3, EBS)
• ArgoCD, GitLab CI/CD, Nexus (artifact registry), Docker, container image build pipelines
• Vault, OpenCost
• Gateway API / Kgateway
• Kubernetes controllers/operators (reconciliation patterns, restart safety) - Go experience is a plus, not required

Engineering Practices We Employ:

• Agile software development
• Infrastructure as Code (IaC)
• Pair programming
• Test-Driven Development (TDD)
• Continuous Delivery

Qualifications

What We Look For:

• 6+ years of experience in software and/or infrastructure engineering
• Bachelor's degree or equivalent experience
• Deep, hands-on production experience operating Kubernetes and AWS at scale, across multiple accounts and regions
• Real operational depth in at least one system we own beyond the cluster - most importantly the observability stack (Prometheus/Alertmanager at scale), but AWS networking, Vault, or artifact/CI infrastructure also count. We are filtering for people who have run these systems, not just used them.
• Strong AWS networking judgment (VPC, peering, Transit Gateway, subnet/CIDR design)
• A track record as a critical reviewer - spotting subtle infrastructure issues and long-term risks before they ship
• Experience leading technical work and mentoring engineers; can manage, clarify, and plan around uncertainty
• Effective communication and the ability to influence design in a product-focused way

Nice to Have:

• Prometheus long-term storage / sharding (Thanos, Cortex, Mimir, or equivalent) run in production
• Experience owning a container image / base image pipeline
• Policy-as-code (Kyverno / OPA) and admission webhook design
• Building claim-based self-service platform capabilities

Additional information

This is a hybrid role requiring 3 days a week in office. CJ is the leader in Performance Marketing. We take pride in our innovative technology, comprehensive data solutions and our people. We equip our teams with advanced tools, training and career development opportunities all to provide modern solutions, strategies and support to deliver high quality results for our clients. We work in an enthusiastic, collaborative team setting that values outstanding performance.

We're a community of creative and passionate problem solvers who go the distance to tackle the tough questions, think creatively, and drive resourceful growth, for our clients—and ourselves. We foster and embody an inclusive and collaborative culture where diverse perspectives are sought, relationships are valued, and people feel accepted with a sense of belonging in expressing themselves authentically. We pride ourselves in having a workplace environment that values both work and play.

Why Our