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Overview

Affirm is seeking a Principal Software Engineer, Load Testing to lead the design and execution of load and performance testing across Affirm's high-scale systems. This is a remote role based in the United States, reporting to Engineering and collaborating with SRE, Platform, and product teams to ensure reliability, latency targets, and scalable performance under peak load.

Responsibilities

Architect and own end-to-end load testing strategy for core services and critical workloads.
Build and maintain scalable load test frameworks and automation to simulate realistic traffic at scale.
Define KPIs (latency, error rate, throughput) and instrument systems to measure performance.
Identify bottlenecks in services, databases, and network components; drive performance improvements.
Collaborate with SRE, Platform, and development teams to plan capacity and optimize deployments.
Create dashboards and reports to communicate performance risks to stakeholders.
Mentor and coach more junior engineers; participate in code reviews and best practices.
Contribute to reliability and resilience initiatives; participate in incident reviews and postmortems.

Requirements

8+ years of software engineering experience with strong focus on performance and reliability engineering.
Deep expertise in load testing and performance tuning for distributed systems.
Proficiency in at least one major programming language (e.g., Python, Java, Go).
Hands-on experience with cloud platforms (AWS or GCP) and containerized environments (Docker/Kubernetes).
Experience with load testing tools (JMeter, Locust, k6, Gatling) and profiling/diagnostics tools.
Strong debugging, triage, and root-cause analysis skills; ability to operate under pressure during incidents.
Excellent communication and collaboration skills; ability to mentor others.

Nice-to-have

Experience in fintech or security-focused environments.
Familiarity with microservices architectures, CI/CD pipelines, and observability tooling (Prometheus, Grafana, OpenTelemetry).

About Affirm

Affirm is a leading fintech company focused on delivering honest financial products and accessible payment solutions. We prioritize customer outcomes, security, and reliability as we scale our platform to millions of users.

Equal Opportunity

Affirm is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees.

Affirm