Senior Staff Engineer, AI Agents

Five9

2d • Hybrid

About The Position

Join us in bringing joy to customer experience. Five9 is a leading provider of cloud contact center software, bringing the power of cloud innovation to customers worldwide. Living our values everyday results in our team-first culture and enables us to innovate, grow, and thrive while enjoying the journey together. We celebrate diversity and foster an inclusive environment, empowering our employees to be their authentic selves. The Senior Staff Engineer, AI Agents, will be responsible for the software architecture and software development of Five9’s AI Agent software platform. As a senior staff individual contributor, you’ll not only be one of the most senior developers on the team, you’ll also mentor junior engineers and set technology direction for platform. You’ll work with other teams, collaborating cross-functionally to make sure complete solutions are delivered. You’ll make some of the most important technology decisions and be in the drivers seat for the platform evolution. Your responsibility extends through deployment and operations, and you will ensure the software platform is scalable, reliable, observable and maintainable by Five9.

Requirements

• 1+ years of experience in software development for GenAI platforms for Customer Support/Customer Experience is REQUIRED.
• 5+ years of software development experience in Java.
• 5+ years of experience in enterprise SaaS software development.
• 10+ years of software development experience.
• Bachelor's or advanced degree in computer science, computer engineering or similar.
• Expert-level proficiency in Java and JVM-based frameworks.
• Strong understanding of object-oriented design, design patterns, clean code, refactoring, and code quality best practices.
• Deep experience designing and building distributed, event-driven systems with high reliability and low latency.
• Expertise in API design (REST/gRPC), service contracts, and backward-compatible evolution.
• Strong familiarity with LLMs, prompt orchestration, function calling, and multi-agent reasoning workflows.
• Experience building AI-enabled microservices, including integrating LLM providers, embeddings, vector databases, RAG pipelines, and structured output validation.
• Solid understanding of model latency, throughput, caching strategies, eval frameworks, and ML-specific observability.
• Experience using one or more frontier models from OpenAI, Google, or open source.
• 5+ years experience in building enterprise SaaS software.
• Expertise with public cloud software development platforms, AWS, GCP or Azure. Preference for GCP experience (Five9 is on GCP).
• Strong familiarity with networking fundamentals: HTTP/2/3, gRPC, load balancing, API gateways, service meshes.
• Strong command of SRE principles: SLIs/SLOs, error budgets, incident response, root cause analysis.
• On-call experience, including incident handling, troubleshooting, and service remediation.
• Experience designing systems for observability: tracing, logging, metrics, profiling.
• Knowledge of performance optimization—CPU, memory, threading, concurrency, GC tuning.
• Hands-on experience running 24×7 global enterprise SaaS systems in production.
• Familiarity with authentication/authorization technologies (OAuth2/OIDC, JWT, mTLS).
• Understanding of secure coding practices, data protection, and enterprise SaaS compliance needs (SOC2, GDPR, HIPAA).
• Ability to drive end-to-end architecture for complex platforms, from requirements → design → implementation → deployment.
• Skilled at creating architecture docs, ADRs, technical deep-dives, and communicating trade-offs clearly.
• Strong understanding of eventing, CQRS, streaming, pub/sub, state machines, and distributed consensus patterns.
• Ability to mentor and elevate teams—code reviews, design guidance, pairing, coaching junior engineers.
• Strong communication skills; capable of explaining technical decisions to: Engineering leadership Product & UX Support, SRE, QA, and Solutions Engineering
• Demonstrated ability to collaborate across orgs to deliver complete, integrated product experiences.
• Ability to set technical direction for the platform and influence roadmaps.
• Ownership mentality across the entire SDLC—design → implementation → CI/CD → monitoring → production operations.
• Exceptional judgment in balancing innovation vs reliability, short-term velocity vs long-term maintainability.
• Ability to decompose large initiatives into deliverable components, driving execution with high accountability.

Nice To Haves

• Nice to Have: Spring Boot,
• Experience in using AI to accelerate software development, using tools like Claude Code or Microsoft CoPilot

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. We also offer 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
• Number of Employees: 1,001-5,000 employees