Mid Level Software Tester Jobs in Naperville, IL

About the Role

IAA is seeking a highly experienced Staff Engineer to join the US Operations Platform organization. This role is focused on modernizing and scaling mission-critical operational applications that support auction, logistics, titles, payments, and yard operations across the United States. You will provide hands-on technical leadership in evolving legacy systems into modern, cloud-native .NET applications, while improving reliability, performance, and long-term maintainability.

Key Responsibilities

• Lead application modernization initiatives, including migration from legacy .NET Framework to modern .NET (.NET Core / latest LTS).
• Drive architectural design for scalable, modular services and APIs supporting high-volume operational workflows.
• Partner with Product and Architecture to decompose monolithic applications into well-defined domains and services.
• Define and implement modern data-access patterns using ORMs, repository patterns, and controlled schema migrations.
• Improve system performance, resilience, and fault tolerance through sound design practices (timeouts, retries, idempotency, and graceful degradation).
• Establish and enforce engineering standards for code quality, testing, and maintainability.
• Embed observability into applications using structured logging, metrics, and distributed tracing (OpenTelemetry).
• Design secure-by-default application patterns including authentication, authorization, secrets management, and secure coding practices.
• Lead technical discovery and solution design for complex, cross-team initiatives.
• Mentor senior and mid-level engineers through design reviews, code reviews, and hands-on technical guidance.
• Support and coordinate "level 3" incidents including after hours as necessary
• Collaborate closely with Infrastructure, Security, Data, and Operations teams to ensure solutions meet operational and compliance requirements.

Qualifications

• 8+ years of professional software engineering experience, with significant time spent modernizing large-scale applications.
• Demonstrated experience operating at a Staff or Principal Engineer level, influencing architecture and technical direction.
• Deep expertise in C#, .NET, .NET Core, and modern application development practices.
• Strong experience designing RESTful APIs and service-oriented or domain-driven architectures.
• Hands-on experience modernizing legacy systems and databases in production environments.
• Strong understanding of relational databases and modern data-access strategies.
• Experience with cloud platforms (Azure preferred) and cloud-native application patterns.
• Excellent communication skills with the ability to clearly explain technical tradeoffs to engineering and business stakeholders.
• Proven ability to lead through influence, mentor engineers, and raise overall engineering quality.

Bonus Experience

• Experience with high-throughput, transaction-heavy operational systems.
• Exposure to event-driven or asynchronous architectures.
• Experience modernizing applications in regulated or compliance-sensitive environments.
• Familiarity with front-end modernization (e.g., React) as part of full-stack initiatives.

IAA Holdings, LLC (IAA)

IAA Holdings, LLC (IAA), a Ritchie Bros. Auctioneers company (NYSE: RBA) and (TSX: RBA), is a trusted global marketplace for insights, services, and transaction solutions for commercial assets and vehicles. Leveraging leading-edge technology and focusing on innovation, IAA's unique platform facilitates the marketing and sale of total-loss, damaged and low-value vehicles. IAA serves a global buyer base - located throughout over 170 countries - and a full spectrum of sellers, including insurers, dealerships, fleet lease and rental car companies, and charitable organizations. Buyers have access to multiple digital bidding and buying channels, innovative vehicle merchandising, and efficient evaluation services, enhancing the overall purchasing experience. IAA offers sellers a comprehensive suite of services aimed at maximizing vehicle value, reducing administrative costs, shortening selling cycle time and delivering the highest economic returns.

RB Global full-time employees are offered medical, dental, vision, and basic life insurances. Employees are able to enroll in our company's 401k plan and RB Global will match 100% for the first 4% contributed.  Employees will also receive 15 days of PTO each year.