Senior Software Engineer

Five9

37d • $90,700 - $252,200 • Hybrid

About The Position

Five9 is seeking a Senior Software Engineer to rapidly modernize our internal platform tooling and drive full-stack engineering maturity. This is primarily a hands-on developer role — you will own the transformation of existing internal tools to be 12-factor compliant, building polished front-end interfaces alongside robust back-end services, and embedding world-class telemetry (Grafana, Prometheus, Loki) throughout the platform. You will also provide architectural direction for software supporting our Infrastructure-as-a-Service (IaaS) platforms, orchestration systems, and platform engineering initiatives. You will champion modern 12-factor application design, transition legacy pipelines into Kubernetes-native GitOps workflows, and mentor mid-tier developers — all while keeping shipping velocity high. This is a private cloud/on-premise infrastructure position. We build and manage our own bare-metal and virtualized data center footprint. Do not apply if your experience is exclusively in public cloud environments (AWS, GCP, or Azure). Candidates must have hands-on, practical experience with physical/on-premise hardware orchestration, hypervisors, and managing Kubernetes on bare-metal/private-cloud layers.

Requirements

• 8+ years of software engineering with proven technical leadership and architectural design experience.
• Strong front-end skills (React or Vue) alongside deep back-end experience — you are comfortable owning the full request lifecycle from UI click to database.
• Deep, hands-on expertise with Grafana, Prometheus, and Loki — not just deploying them, but designing dashboards, writing PromQL/LogQL, building exporters, and enforcing instrumentation standards across a team.
• Demonstrated experience auditing and refactoring real applications to be 12-factor compliant in a production environment.
• Deep expertise in Python and Go (Golang) for building distributed systems and enterprise APIs.
• CKA or CKAD strictly required (CNCF).
• Hands-on experience with on-premise clusters, preferably Rancher.
• Strong experience with OpenStack, private cloud environments, and foundational infrastructure networking.
• Extensive experience with Ansible, AWX/Tower, Harbor, and GitLab.
• Proven expertise in SDLC practices, code refactoring, automated testing, and GitOps (ArgoCD).

Nice To Haves

• Experience designing and shipping internal developer portals or operational tooling used by platform and SRE teams.
• Hands-on experience with distributed tracing (Jaeger, Tempo, or OpenTelemetry) to complement the Grafana/Prometheus/Loki stack.
• Deep practical experience implementing SRE principles at large-scale enterprise.
• Familiarity with Bare Metal as a Service (BMaaS) provisioning and integration.
• Experience navigating ITIL change management processes within highly automated CI/CD frameworks.
• Experience establishing engineering standards and driving a culture of accountability and continuous improvement.

Responsibilities

• Rapidly audit and refactor existing internal tools and services to strictly comply with 12-factor application principles — configuration via environment, stateless processes, explicit dependency declarations, disposability, and dev/prod parity.
• Own end-to-end delivery of modernized services: back-end APIs (Go/Python) paired with clean, functional front-end interfaces (React or Vue) that surface platform data and controls to internal users.
• Decompose monolithic or ad-hoc scripts into properly structured, independently deployable services with clearly defined interfaces.
• Build and maintain internal web UIs using modern front-end frameworks (React or Vue) — dashboards, tooling consoles, and operational interfaces that teams actually want to use.
• Design and develop robust REST/gRPC back-end APIs in Go and Python following clean architecture patterns.
• Ensure front-end and back-end components are instrumented end-to-end with traces, metrics, and structured logs from day one.
• Own the platform observability stack: design, implement, and continuously improve our Grafana, Prometheus, and Loki deployment for all internal services.
• Define and enforce instrumentation standards — every new or refactored service must ship with meaningful RED metrics, structured JSON logs forwarded to Loki, and distributed traces.
• Build and maintain Grafana dashboards and alerting rules that provide actionable signal for on-call engineers; define and manage SLIs/SLOs across critical platform services.
• Implement Prometheus exporters for custom internal services and integrate alerting with PagerDuty or equivalent.
• Drive log aggregation strategy with Loki — label taxonomy, retention policies, and LogQL query libraries for common operational queries.
• Design, develop, and support robust APIs and automation services from scratch using Go and Python.
• Conduct architecture reviews and enforce design standards across the platform engineering team.
• Drive the modernization of legacy platform components with a bias toward simplicity and operational transparency.
• Lead the refactoring of existing deployment pipelines to be fully Kubernetes-native.
• Define and implement disciplined software release cycles using GitLab CI/CD and ArgoCD for GitOps-driven deployments.
• Establish automated testing gates (unit, integration, contract) as hard requirements in the pipeline.
• Mentor mid-tier developers, establish coding standards, enforce peer reviews, and reduce technical debt.
• Improve engineering maturity across the team — instill a culture of instrumentation-first development where observability is never an afterthought.
• Maintain and overhaul technical documentation; make it easy for new engineers to onboard and contribute.
• Drive enterprise-grade infrastructure automation and orchestration using Ansible, AWX, and Terraform.
• Oversee the secure and highly available architecture of core lifecycle services such as Harbor and GitLab.

Benefits

• Health, dental, and vision coverage, beginning on the first day of employment.
• Five9 covers 100% of the employee portion of the health, dental and vision coverage and shares a high portion of the dependent cost.
• Short & Long-Term Disability, Basic Life Insurance, and a 401k saving plan with employer matching.
• Access to an innovative mental health support platform that offers personalized care and resources in areas such as: therapy, coaching and self-guided mindfulness exercises for all covered employees and their covered dependents.
• Generous employee stock purchase plan.
• Paid Time Off, Company paid holidays, paid volunteer hours and 12 weeks paid parental leave.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed