Senior Applications Developer

Job ID: R_330847Company: Marsh McLennanLocation: 1301 Fifth Avenue, Rainier Tower, Seattle, WA 98101, United States of AmericaJob Type: RegularCategory: TechnologyIndustry: Real EstateSalary: 155000Posted Date: 2026-07-29Contact Email: View email address on click.appcast.io a Senior Software Developer, you will design, develop, implement, and support high-performance, scalable .NET scientific simulation platforms using agile practices. This hands-on role requires both independent work and collaboration to enhance usability, performance, automation, and scalability.We will count on you to:Develop customer-facing online experiences, including portals, licensing tools, help content, and news features.Build high-performance applications in C#/.NET using modern development standards and best practices.Support migration and development efforts across Azure and other cloud platforms.Collaborate with actuaries, QA, domain experts, and product partners to design, test, and support software tools.Enhance telemetry, reporting, dashboards, and user feedback loops to improve product usability and performance.What you need to have:10+ years of software development experience.Expert-level proficiency in C# (v12), .NET (v8), and Visual Studio 2022/2023.Strong knowledge of threading, async/await, LINQ, pattern matching, interoperability, and REST API design.Experience architecting maintainable, flexible, scalable, cloud-native solutions, especially in Azure.Excellent communication, teamwork, and self-motivation skills, with experience working directly with users in an Agile environment.Proven ability to ship commercial software or customer-facing online experiences.Ability to work both remotely and in person, with willingness to travel occasionally.Experience with SQL, Protobuf, and interactive charting/graphing packages.What makes you stand out:Experience with Object-Oriented Analysis and Design (OOAD).Familiarity with Angular, WebAssembly, HTML, CSS, TypeScript, JavaScript, and jQuery.Additional background in Python, Kubernetes, C++, C++/CLI, or a strong mathematics foundation.Experience working with LLMs and AI agent technologies.Why join our team:We help you be your best through professional development opportunities, interesting work and supportive leaders.We foster a vibrant and inclusive culture where you can work with talented colleagues to create new solutions and have impact for colleagues, clients and communities.Our scale enables us to provide a range of career opportunities, as well as benefits and rewards to enhance your well-being. At Guy Carpenter, a Marsh business, you can be your best. We work on challenges that matter with colleagues who help bring out our best. Our uniquely collaborative environment will empower you to focus on your personal and professional success, learning from top specialists in the (re)insurance industry and leading you towards a rewarding and impactful career.Guy Carpenter is a business of Marsh (NYSE: MRSH), a global leader in risk, reinsurance and capital, people and investments, and management consulting, advising clients in 130 countries. With annual revenue of over $27 billion and more than 95,000 colleagues, Marsh helps build the confidence to thrive through the power of perspective. For more information about Guy Carpenter, visit guycarp.com, or follow us on LinkedIn and X.Marsh is committed to embracing a diverse, inclusive and flexible work environment. We aim to attract and retain the best people and embrace diversity of age background, disability, ethnic origin, family duties, gender orientation or expression, marital status, nationality, parental status, personal or social status, political affiliation, race, religion and beliefs, sex/gender, sexual orientation or expression, skin color, veteran status (including protected veterans), or any other characteristic protected by applicable law. If you have a need that requires accommodation, please let us know by contacting View email address on click.appcast.io is committed to hybrid work, which includes the flexibility of working remotely and the collaboration, connections and professional development benefits of working together in the office. All Marsh colleagues are expected to be in their local office or working onsite with clients at least three days per week. Office-based teams will identify at least one “anchor day” per week on which their full team will be together in person.Skillsc#.netvisual studioazuresqlrest apiprotobufobject-oriented analysis and designteamworkcommunicationangularhtmlcssjavascripttypescriptkubernetesc++c++/climathematics