Marsh & Mclennan is a premier global professional services firm specializing in risk, strategy, and people. As a Software Engineer at Marsh & Mclennan, you will play a critical role in designing, building, and maintaining high-performance software systems that power global risk management, insurance brokerage, and consulting platforms. The solutions you develop directly impact how multinational corporations analyze risk, allocate capital, and protect their workforces.

In this role, you will work on enterprise-scale applications that require high availability, robust security, and seamless data processing capabilities. Engineering teams at Marsh & Mclennan are tasked with modernizing legacy systems, migrating core services to the cloud, and developing sophisticated APIs that integrate with diverse backend systems. This position offers a unique blend of complex technical challenges and strategic business influence, making it an exciting environment for engineers who want their code to have a tangible global impact.

Whether you are optimizing database queries to handle massive financial datasets or architecting microservices to support real-time risk analytics, your work will directly drive the firm's digital transformation. You will collaborate closely with cross-functional teams of product managers, data analysts, and system architects to deliver reliable, user-focused software that maintains Marsh & Mclennan's position as an industry leader.

The questions you will face during the hiring process are designed to evaluate your core technical skills, problem-solving methodology, and behavioral alignment. While these questions are representative of real reported interview experiences, they are intended to highlight common patterns and key evaluation themes rather than serve as a memorization list.

Technical & Domain Knowledge

These questions assess your familiarity with core programming languages, web frameworks, and database management systems, particularly within the Microsoft tech stack which is heavily utilized across the firm.

• Explain the lifecycle of an ASP.NET MVC request and how routing is handled.
• How do you implement dependency injection in a .NET Core application, and what are its primary benefits?

Preparing for your interviews at Marsh & Mclennan requires a balanced approach that demonstrates both your technical execution and your collaborative mindset. You should approach your preparation by focusing on the core criteria that the hiring team uses to evaluate potential candidates.

Role-Related Knowledge – You must demonstrate a deep understanding of the technologies specified in the job description. For many teams, this means showing proficiency in C#, .NET, SQL, and modern web frameworks. Be prepared to explain not just how to use these tools, but why specific architectural patterns are chosen.

Problem-Solving Ability – Interviewers want to see how you dissect complex, ambiguous problems. Whether you are writing an algorithm or designing a system, focus on communicating your thought process clearly. Walk through your assumptions, evaluate trade-offs, and structure your solution systematically before writing any code.

Agile Adaptability & Leadership – Marsh & Mclennan relies heavily on Agile methodologies. You should be ready to discuss your experience working in sprints, managing technical debt, and collaborating with cross-functional stakeholders. Show how you take ownership of deliverables and foster a healthy, productive team environment.

The interview process for a Software Engineer at Marsh & Mclennan is structured to thoroughly evaluate both your technical competence and cultural alignment. Depending on the team and location, the process typically spans three to four stages, blending automated assessments with live technical and behavioral panels.

The initial phase often begins with an automated screening, which may consist of an online aptitude test, a basic coding assessment, or an AI-powered video interview. This initial step is designed to evaluate your resume, communication skills, and foundational technical knowledge. Following a successful screen, you will progress to one or more technical rounds. These rounds focus heavily on live coding (typically Leetcode easy-to-medium level questions), SQL query design, and detailed discussions regarding your past projects and architectural choices.

For mid-to-senior positions, you will also face a system design round where you are expected to map out API communications and backend integrations. The final stages of the process consist of managerial and behavioral interviews. Here, a panel of team members and hiring managers will assess your alignment with corporate values, your experience in Agile environments, and your soft skills, followed by final HR discussions and salary negotiations.

This visual timeline outlines the typical progression from the initial automated screen to the final hiring manager decision. Use this sequence to pace your study plan, ensuring you master both the algorithmic coding challenges early on and the system architecture and behavioral scenarios for the final stages.

To succeed in the Marsh & Mclennan interview process, you must perform strongly across several core competencies. Understanding exactly what interviewers look for in each area will help you tailor your preparation.

Object-Oriented Development & Web Frameworks

This area evaluates your hands-on coding capabilities and your understanding of modern software development practices, particularly within the Microsoft ecosystem. Strong performance means writing clean, maintainable, and idiomatic code while explaining the architectural patterns behind your implementation.

Be ready to go over:

• C# & .NET Core – Deep understanding of memory management, asynchronous programming, and dependency injection.
• ASP.NET MVC & Web APIs – Designing clean RESTful endpoints, handling state, and managing security protocols.
• Frontend Integration – Integrating backend services with frontend technologies such as JavaScript, jQuery, or modern SPA frameworks.
• Advanced concepts (less common) – Legacy code refactoring, multi-threading optimization, and memory leak debugging.

Example scenarios:

• "Explain how you would secure a Web API endpoint and manage user authentication across services."
• "Walk me through how you would refactor a tightly coupled legacy class to make it testable using dependency injection."

System Design & Infrastructure

For enterprise systems, scalability and reliability are paramount. Interviewers will assess your ability to design robust system architectures, manage data flow, and utilize modern cloud and containerization tools.

Be ready to go over:

• API Design & Integration – Designing scalable APIs and establishing reliable communication protocols between microservices.
• Database Architecture – Designing normalized relational schemas, optimizing complex SQL queries, and utilizing indexing strategies.
• Cloud & DevOps Foundations – Utilizing cloud services (AWS), containerization (Docker, Kubernetes), and basic Linux scripting.
• Advanced concepts (less common) – Designing for ITIL/ITSM compliance, infrastructure management, and utilizing automation tools.

Example scenarios:

• "Design an API gateway that routes requests to multiple backend microservices while handling rate limiting."
• "Describe how you would set up a continuous deployment pipeline for a containerized .NET application on AWS."

Agile Methodology & Team Collaboration

Because Marsh & Mclennan emphasizes structured team environments, you will be evaluated on how you navigate team dynamics, manage project workflows, and handle organizational challenges.

Be ready to go over:

• Agile Practices – Managing sprint deliverables, running retrospectives, and handling blockers.
• Conflict Resolution – Navigating technical disagreements or interpersonal issues within a development team.
• Project Ownership – Demonstrating how you take a project from initial requirements to successful production deployment.

Example scenarios:

• "Tell me about a time when a sprint retrospective revealed a major bottleneck in your team's workflow and how you addressed it."
• "How do you handle a situation where a product owner requests a feature that conflicts with the technical architecture of the system?"