Senior Software Engineer

Socket.dev; Annapolis (MD); Hybrid; USD 130,000 - 180,000; Full time

Benefits offered by this job

Comprehensive health coverage

A Hybrid work environment

Opportunity for advancement and growth

Catered Events, Snacks, Drinks – You\'

Birthday and Life Celebrations

Two annual parties in a year

Job summary

FacilityOS is seeking a Sr. Back-End Engineer to design, develop, and modernize backend services within our unified platform. You’ll navigate legacy systems, apply strong architecture principles, and contribute to efficient delivery through collaboration and code quality.

The role is hybrid and requires coming into the office three times per week. Ideal candidates have extensive .NET experience, proficiency in RESTful services, and a passion for scalable SaaS architectures.

Qualifications

• 8+ years of backend .NET Framework / .NET Core development using C#.
• Ability to quickly understand complex legacy systems, identify key integration points.
• Experience applying the Strangler Fig pattern or similar modernization approaches.
• Strong OO design, patterns, and clean architecture for maintainable software.
• Experience writing unit tests and quality-focused development practices.
• Experience designing RESTful services.
• Experience building cloud-native SaaS and PaaS applications.
• Solid knowledge of Microsoft SQL Server and T-SQL.
• Ability to collaborate with existing engineering teams.
• Proactive, curious, and detail-oriented mindset with a focus on quality.
• Passion for technology and modern engineering practices.
• Ability to self-manage priorities and deliver with minimal supervision.
• Strong team-player attitude across engineering, architecture, and product stakeholders.

Responsibilities

• Design, develop, review, and maintain backend web applications and services across the FacilityOS platform.
• Understand platform architecture, legacy components, integration points, and modernization opportunities.
• Collaborate with the engineering team to align with architectural principles and delivery goals.
• Contribute to legacy modernization using incremental, low-risk approaches such as strangler patterns.
• Maintain high code-quality standards through code reviews, unit testing, and tooling.
• Participate in peer code reviews, providing constructive feedback.
• Troubleshoot and resolve issues across environments with root-cause analysis.
• Work with engineering leads, product stakeholders, and project managers to support delivery.
• Research, evaluate, and recommend architectural improvements for the platform.

Skills

C#/.NET

RESTful APIs

Legacy modernization

System design

Unit testing

Cloud-native SaaS/PaaS

SQL Server/T-SQL

Code reviews/mentoring

Job description

About FacilityOS

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.

Duties and 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.

Skills and Qualifications

• 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.

Why work at FacilityOS?

We work hard and play hard and we do both with passion and respect for one another. Our company promotes a fast-paced, fun, friendly, and highly collaborative work environment that provides:

Benefits

• Comprehensive health coverage


• A Hybrid work environment


• Opportunity for advancement and growth


• Catered Events, Snacks, Drinks – You won't go Hungry!


• Birthday and Life Celebrations


• Two annual parties in a year

FacilityOS Commitment

We believe that a diverse team is the key to innovation and growth. We are an equal opportunity employer that value diversity at our company and encourage all candidates to apply. We do not discriminate based on race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status. FacilityOS will accommodate individuals with disabilities through each stage of the recruitment and selection process. Please advise us of any needs when your interview is booked, and we will do our best to meet your needs. Please note that all candidates must be legally eligible to work in Canada or United States. FacilityOS thanks all candidates for their interest, however only those selected to continue in the process will be contacted.

Background and Reference Checks

Any offer of employment may be conditional upon full background checks including a criminal record check, a credit check and employment and educational verifications. A reference check will also be conducted. We may use artificial intelligence (AI) tools to support parts of the hiring process such as reviewing applications. These tools assist the recruitment team but do not replace human judgment. All advancement and hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us or click here.