Performance Test Engineer

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. 

About the Role

The Performance Test Engineer will be a core member of Five9's Performance Engineering team, responsible for designing, building, and executing performance tests across our cloud contact center platform. The ideal candidate has hands-on experience creating realistic workload models, running load and stress tests, and turning test results into clear, actionable findings for development teams. They will apply modern AI-assisted tooling to accelerate test analysis and anomaly detection, helping Five9 deliver consistently fast and reliable product experience.

Key Responsibilities

• Design, develop, and maintain performance test scripts and scenarios using tools such as k6, Gatling, JMeter, or Python
• Build and maintain realistic workload models that accurately represent production traffic patterns and user behavior
• Define and document performance test objectives, entry/exit criteria, and service level objectives (SLOs)
• Execute a range of test types including baseline, load, stress, soak, spike, and scalability tests
• Analyze test results to identify bottlenecks, regressions, and areas of concern; produce clear written findings and recommendations
• Collaborate closely with developers, QA engineers, and architects to share results and support remediation efforts
• Set up and maintain performance test environments and test data in alignment with production configurations
• Integrate performance tests into CI/CD pipelines to enable continuous performance validation
• Define and configure monitoring dashboards and alert thresholds using observability platforms (e.g. Datadog, Grafana, Prometheus)
• Triage performance-related defects and contribute to root cause analysis investigations
• Maintain performance test documentation, test plans, and results archives
• Leverage AI-assisted tooling for automated anomaly detection, intelligent baselining, and accelerated result analysis
• Use AI/ML-powered AIOps platforms to identify trends, predict regressions, and reduce mean time to detection (MTTD) for performance issues

Requirements

• 4-7 years of hands-on experience in performance testing or performance engineering
• Practical experience writing and maintaining test scripts in one or more of: k6, Gatling, JMeter, or equivalent
• Solid understanding of performance test types and when to apply them (load, stress, soak, spike, scalability)
• Experience defining workload models and translating production metrics into test scenarios
• Proficiency with application performance monitoring tools (e.g. Datadog, New Relic, Grafana, Prometheus, AppDynamics)
• Ability to interpret test results and thread/heap dumps, identify bottlenecks, and communicate findings clearly to technical and non-technical stakeholders
• Experience integrating performance tests into CI/CD pipelines (e.g. Jenkins, GitLab CI, GitHub Actions)
• Scripting or programming skills in at least one language (Python, JavaScript/Node.js, Java, or Groovy)
• Familiarity with AI/ML concepts applied to testing: anomaly detection, intelligent baselining, AIOps, or LLM-assisted diagnostics
• Experience testing web applications and APIs (REST, gRPC, WebSocket) under realistic concurrency
• Strong written and verbal communication skills; ability to present findings and drive discussions with engineering teams

Nice to Have

• Experience testing VoIP, real-time communications, or contact center platforms
• Familiarity with containerized test execution environments (Docker, Kubernetes)
• Exposure to chaos engineering practices (e.g. Chaos Monkey, Gremlin) as a complement to performance testing
• Experience with AI observability or AIOps tools (e.g. Dynatrace Davis AI, Datadog Watchdog, Arize)
• Knowledge of distributed tracing tools (e.g. Jaeger, Zipkin, OpenTelemetry) for request-level performance analysis

Workplace location: This role is hybrid and requires 3 days a week in our Porto office.

Benefits:

• Five9 Shares
• Bonus Scheme
• 10% Flexi Benefit
• Meal Allowance
• Medical Insurance
• Life Insurance 
• 25 day Annual Leave + Public Holidays

Five9 embraces diversity and is committed to building a team that represents a variety of backgrounds, perspectives, and skills. The more inclusive we are, the better we are. Five9 is an equal opportunity employer. 

View our privacy policy, including our privacy notice to California residents here:  https://www.five9.com/pt-pt/legal.  

Note: Five9 will never request that an applicant send money as a prerequisite for commencing employment with Five9.