Senior Software Engineer, Backend (OS)

SimSpace serves as an AI Proving Ground where organizations can confidently train, test, and outmaneuver adversaries in any environment. Trusted by allied governments, militaries, enterprises, and research institutions worldwide, SimSpace enables adaptive, AI-ready defenses that stay ahead of evolving threats. Founded in 2015 by experts from U.S. Cyber Command and MIT Lincoln Laboratory, the platform unifies training, testing, and validation in a realistic, live-fire simulation—helping teams evaluate security investments, optimize performance, and compress cyber readiness cycles from months to days.

Why join SimSpace? We are an organization that is focused on building our culture and mindfully enhancing our atmosphere every day which is why we have collaborated on an integral value system. Our governing philosophy of being Human Centered is deeply embedded within our value system. We apply this philosophy to every one of our internal team members, external clients, and their customers.

How Do We Work? We believe that people are at the center of everything we do. SimSpace fosters a culture of continuous learning, curiosity, and professional growth. That belief shows up in action: in-house training, internal and external learning platforms, cyber conferences, industry events, and dedicated time for skill development. Our people are empowered to shape their careers - and it shows. Year over year, SimSpace consistently outperforms industry benchmarks in internal mobility, promotions, and total rewards growth.

Who Thrives Here? We are a team of innovators, protectors, and problem-solvers. We believe diversity of thought and experience fuels better solutions, and we’re committed to building teams that reflect the communities we serve. Whether you’re remote or office-based, you’ll collaborate with talented colleagues across departments and time zones, united by the mission to create a safer digital world.

We invite you to apply today!

The Role

The Senior Software Engineer on the Attack & User Emulation team builds the core endpoint capabilities and distributed orchestration services that power realistic offensive security and simulated user personas across cyber ranges. By operating below standard application abstractions, this role ensures simulated users interact with OS facilities (sessions, processes, UI, and networking) to generate high-fidelity system and security telemetry for training and evaluation.

In this role, you will work primarily on our Go-based endpoint agent while contributing across Kotlin backend services, messaging, and orchestration. You will solve distinctive technical challenges around operating-system behavior, privilege boundaries, and dynamic desktop/web automation across thousands of virtual environments.

What the Team Owns

• High-fidelity attack and user emulation capabilities for cyber range environments.

• Cross-platform endpoint agents (Windows/Linux) and backend orchestration services.

• System reliability, security, and telemetry fidelity across active virtual systems.

• Operational interfaces for AI-driven personas and higher-level range automation.

What You'll Do

• Design, build, and operate production software in Go, python, and Kotlin for attack and user emulation frameworks.

• Develop deep operating-system integrations on Windows and Linux using native OS APIs, session management, process execution, and system facilities.

• Improve system reliability, security, testability, and observability across message-driven architectures operating at scale.

• Solve high-fidelity emulation problems, including desktop/web automation, privilege boundaries, input simulation, and realistic user timing.

• Collaborate with backend, security, and AI engineering teams to define reusable primitives and APIs.

• Conduct code and design reviews, mentor team members, and elevate the team's platform-level engineering craft.

What Success Looks Like

• By 30 days: Build familiarity with the Go endpoint agent, contribute to active feature development, and debug cross-platform OS behaviors.

• By 60 days: Lead the design and delivery of a new endpoint emulation capability or native system integration.

• By 90 days: Drive architectural improvements across distributed messaging and agent subsystems while mentoring junior/mid-level engineers.

Required Qualifications

• 6+ years of hands-on software engineering experience delivering and operating production software.

• Deep practical experience with Windows or Linux systems development, working below application-level abstractions (e.g., native APIs, process/session management, eBPF, IPC, or security contexts).

• Strong proficiency in Go, or demonstrated expertise in another systems language with the ability to become productive in Go quickly.

• Experience with JVM languages (Kotlin/Java) and message-driven, asynchronous architectures.

• Demonstrated ability to reason about complex OS failure modes, trade-offs between fidelity and complexity, and distributed system stability.

Preferred Qualifications

• Building production endpoint, monitoring, remote management, or EDR/security agents.

• Experience with desktop/browser automation, accessibility APIs, or computer vision.

• Familiarity with hypervisors, VDI, endpoint security telemetry, adversary emulation, or tool integration for AI agents.

Technology Environment

Go, Kotlin, Java, Python, RabbitMQ, Kubernetes, Docker, Spring Boot, VMware, Windows, Linux

We’re proud to offer a competitive and comprehensive package designed to support your well-being, growth, and success:

• Compensation. Base monthly pay range: 1,500,000 CRC - 2,500,000 CRC reflecting our confidence in your expertise and impact, with the opportunity for annual bonuses tied to company performance and individual contributions.

• Health & Wellness. Private medical, dental, vision, and life benefits.

• Mental Health Support. Access to company-paid counseling, coaching, and resources for you and your family through Spring Health.

• Parental Leave. Paid leave plans to support you and your loved ones during life’s most important moments.

• Ownership Opportunities. Equity stock options at hire, with annual performance-based grants—become an invested stakeholder in our shared success.

• Continuous Learning. Access a LinkedIn Learning membership to prioritize your personal and professional development.

• Social Connections. Monthly reimbursements for meaningful connections with teammates through our SocialSpace Community.

SimSpace is an Equal Opportunity Employer:

In compliance with federal law, all persons hired will be required to verify identity and eligibility to work in the United States and to complete the required employment eligibility verification document form upon hire.

SimSpace is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, pregnancy, genetic information, disability, status as a protected veteran, or any other protected category under applicable federal, state, and local laws. We are committed to providing an inclusive and welcoming environment for all members of our staff, clients, volunteers, subcontractors, vendors, and clients.

Research shows that women and people from underrepresented groups only apply to jobs if they meet all of the qualifications. However, no one ever meets 100% of the qualifications. SimSpace encourages you to break that statistic and to apply. We look forward to your application!

We also consider qualified applicants regardless of criminal histories, in accordance with applicable law. We are committed to providing reasonable accommodations for qualified individuals with disabilities in our job application procedures. If you need assistance or accommodation due to a disability, please contact careers@simspace.com.

SimSpace does not accept unsolicited resumes from employment agencies.

Actual compensation for the position is based on a variety of factors, including, but not limited to affordability, skills, qualifications and experience, and may vary from the range.