Performance & Resiliency Test Engineer/Performance Engineer/Performance Tester

Location: O'Fallon, MO- Onsite

Work Model: Hybrid (4 Days Onsite, 1 Day Remote)- hybrid

Skills: Performance Testing, Resiliency Testing, Failover Testing, Recovery Testing, TCP/IP, Packet Analysis, Load Testing, Soak Testing, Capacity Testing, Network Testing, Automation Testing, High Availability, ISO 8583, Active-Active Architecture.

Job Summary: We are seeking a highly skilled Performance & Resiliency Test Engineer to define and execute validation strategies for functional behavior, transaction integrity, performance, failover, recovery, monitoring, and production readiness of mission-critical systems. The ideal candidate will have expertise in performance engineering, resiliency testing, network protocols, and high-availability platforms.

Responsibilities: Develop and execute end-to-end test plans across lab, staging, and lower environments. Validate traffic movement and persistent TCP connections during maintenance and failure scenarios. Ensure no unacceptable message loss, duplication, ordering issues, or customer-visible service disruptions. Perform functional, integration, regression, negative, load, soak, capacity, failover, and recovery testing. Validate proxy bypass and return-to-legacy recovery procedures. Reproduce defects, analyze logs and packet captures, and support root cause analysis. Define test evidence, acceptance criteria, certification results, and operational readiness sign-offs. Collaborate with development, infrastructure, and operations teams to improve system resiliency.

Required Skills: Performance Testing, Resiliency Testing, Network Testing, and Integration Testing. Strong TCP/IP networking and packet-level troubleshooting experience. Experience with automated test frameworks and failure-injection techniques. Hands-on experience with performance and capacity testing tools. Strong defect analysis, debugging, and technical documentation skills. Experience validating high-availability and failover architectures.

Preferred Qualifications: Experience with Financial Messaging, ISO 8583, Payment Processing, Telecom, or other high-availability transaction platforms. Knowledge of Proxy, Load Balancer, Network Service, and Active-Active Failover testing. Exposure to distributed systems and high-throughput transaction environments.