Software Developer II (Mid-Level) jobs in United States
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3Si · 8 hours ago

Software Developer II (Mid-Level)

positionAshburn, VA
timeFull-time
remoteOnsite
seniorityMid, Senior Level
date5+ years exp

3Si Security Systems is a global leader in innovative security technology dedicated to making the world safer. The Mid-Level Software Developer is responsible for participating in the full software development lifecycle, including design, development, testing, and implementation of enhancements to enterprise-level applications.

GPSPhysical SecuritySecurity
badNo H1BnoteU.S. Citizen Onlynote

Responsibilities

Participate in full software development lifecycle activities, including design, development, testing, debugging, and implementation
Define and document functional requirements based on stakeholder input
Design and develop scalable software solutions using C# and .NET
Collaborate with other developers and cross-functional teams to ensure technical alignment with project goals
Utilize development tools such as Visual Studio, Git, Jira
Work with technologies including REST/ServiceStack, WPF, Progress/Telerik UI Toolkit
Support and maintain client and server utilizing REST and HTTPS protocols
Perform other duties as needed to support the company’s mission and project requirements

Qualification

C#.NETWPFRESTful APIsVisual StudioGitJiraProblem-solvingCommunicationCollaboration

Required

Bachelor's degree in Computer Science, Information Technology, Software Engineering, or a related technical field
Equivalent professional experience may be considered in lieu of formal education
Associate degree in a technical discipline combined with relevant experience and/or industry certifications may also be considered
At least 5 years of related software development experience
Minimum of 3 years of hands-on experience in C#/.NET development
Experience with reusable C# library development and version-controlled environments
Strong understanding of full-stack development practices
Proficiency in C# and the .NET framework
Experience with Windows Presentation Foundation (WPF)
Knowledge of software development best practices and secure coding techniques
Ability to work with RESTful APIs and HTTP network technologies
Skilled in using Visual Studio, Git, and Jira
Strong problem-solving and analytical abilities
Effective communication and collaboration skills
Ability to work independently or within a team environment

Benefits

Competitive benefits

Company

3Si

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Redefined Actionable Intelligence: With a fresh new look and a revolutionary purpose and mission, we are positioned to better serve our clients, partners, law enforcement, and communities with our cutting-edge technologies and real-world experience to deliver redefined actionable intelligence via an integrated platform that significantly impacts the bottom line – and, more importantly, lives.
dateFounded in 1971
location
Malvern, Pennsylvania, USA
people-size201-500 employees
web-link
https://www.3sisecurity.com/

Funding

Current Stage
Growth Stage
Total Funding
$13M
Key Investors
American Capital
2017-06-20Acquired
2002-07-29Series Unknown· $13M

Leadership Team

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Matt Kushner
Chief Executive Officer
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Todd Leggett
CEO
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Recent News

citybiz
3Si Security Systems Appoints Peter Giacalone to Board
2025-09-30
Morningstar.com
Netwatch and 3Si Announce a Strategic Integration to Deliver Next-Level Crime Intelligence and Response
2025-09-24
Morningstar.com
3Si and Flock Safety Partner to Deliver Integrated Intelligence for Law Enforcement Crime Response
2025-09-12
Company data provided by crunchbase