Senior Software Engineer

FacilityOS•Annapolis, MD

5d•Hybrid

About The Position

FacilityOS is a fast-growing company redefining how facilities operate—bringing safety, security, and daily operations into one unified platform used by organizations around the world. As we continue to scale globally, we’re building a team of driven, curious people who want to make an impact. You’ll be part of a dynamic, collaborative culture where individuals are trusted to take ownership, solve meaningful problems, and grow in their careers. Our team comes together in-office twice a week to connect, collaborate, and build momentum. If you’re looking to do your best work alongside a great team in a high-growth environment, FacilityOS is the place to build your career. About the Role: We are looking for a highly capable Sr. Back-End Engineer who can ramp up quickly, collaborate effectively with the existing team, and begin contributing meaningful delivery outcomes within the first few weeks. This role is well suited for someone who is comfortable navigating legacy systems, applying strong architectural principles, and making thoughtful technical decisions that improve delivery throughput without compromising quality. The ideal candidate brings strong backend engineering experience, sound judgment, and the ability to work independently while staying closely aligned with team standards and architectural direction. This role is a hybrid position where you’ll be required to come into our office three (3) times a week.

Requirements

Minimum of 8 years of proven experience in backend .NET Framework / .NET Core web application development using C#.
Proven ability to quickly understand complex legacy systems, identify key integration points, and contribute effectively with limited ramp-up time.
Proven experience applying the Strangler Fig pattern or similar modernization approaches to gradually replace or refactor legacy systems.
Strong experience using object-oriented programming, design patterns, and clean architecture principles to build maintainable, testable software.
Proven experience writing unit tests and applying quality-focused development practices.
Proven experience designing and building RESTful services.
Experience designing and building cloud-native SaaS and PaaS applications.
Solid knowledge of Microsoft SQL Server and T-SQL.
Ability to make sound technical decisions in collaboration with existing engineering teams.
Proactive, curious, and investigative mindset with strong attention to quality and detail.
Passion for technology, continuous improvement, and modern engineering practices.
Ability to self-manage priorities and deliver outcomes with minimal supervision.
Strong team-player attitude with the ability to collaborate across engineering, architecture, and product stakeholders.

Responsibilities

Design, develop, review, and maintain backend web applications and services across the FacilityOS platform.
Quickly develop a working understanding of existing platform architecture, legacy components, integration points, and modernization opportunities.
Collaborate with the engineering team to make sound technical decisions that align with established architectural principles and delivery goals.
Contribute to legacy modernization efforts using incremental, low-risk approaches such as the Strangler Fig pattern where appropriate.
Maintain high code-quality standards through code reviews, unit testing, static code analysis, and the adoption or improvement of engineering tools and standards.
Participate actively in peer code reviews, providing constructive feedback and helping promote maintainable, testable, and scalable solutions.
Troubleshoot and resolve application issues across environments, including staging and production, with a focus on root-cause analysis and sustainable fixes.
Work directly with engineering leads, product stakeholders, and project managers to support business operations and project delivery.
Research, evaluate, and recommend innovative application, automation, and architectural improvements that would benefit the FacilityOS platform.