We are looking for a Senior Software Engineer to serve as the technical lead for SimSpace's internet simulation platform - the system that makes cyber range environments behave like the real internet at the network layer. This is foundational, novel work: you will be designing and building a kernel-level simulation layer that reproduces the observable behavior of worldwide internet routing - correct ASN topology, realistic inter-AS latency, accurate traceroute and MTR output - without instantiating a single virtual router.

The approach is grounded in a patent pending eBPF-based architecture developed at SimSpace, and this role will take that proof of concept into a production-grade system. As the technical lead on a newly formed team, you will set architectural direction, mentor peer engineers, and partner closely with a Principal Engineer and your Engineering Manager to build something that does not yet exist at this fidelity in the industry.

The team is responsible for:
• A persistent, control-plane internet simulation service that serves multiple concurrent cyber ranges without per-range instantiation
• An eBPF-based network simulation layer providing geographically accurate ASN routing, inter-AS latency enforcement, and traceroute and MTR fidelity entirely in kernel space
• Lightweight in-range proxy agents that receive topology configuration from the control plane and handle local packet interception without requiring a full simulation stack in every range
• A topology database encoding real-world ASN-to-CIDR mappings, inter-AS latency models, and geographic placement data that drives the simulation
• Dynamic reconfiguration of the simulated internet topology at runtime without disrupting in-flight traffic

What will you be doing as a Senior Software Engineer II, Network Simulation at SimSpace?
• Own the end-to-end architecture of the eBPF-based routing simulation layer, including XDP and TC hook point design, BPF map structure, and synthetic ICMP TTL-exceeded generation that makes traceroute and MTR behave correctly against the simulated topology
• Design and build the control-plane topology database and the pipeline that compiles real-world internet topology data into a form that in-range agents can consume and apply
• Architect the in-range proxy agent: the lightweight component that bridges the persistent control plane to individual cyber ranges, applying topology configuration locally and handling DNS delegation and traffic forwarding
• Define the interface contract between the control plane and in-range agents, including topology update propagation, graceful degradation when control plane connectivity is interrupted, and agent lifecycle management
• Serve as technical lead for the team - making daily architectural decisions across the full service scope, conducting design reviews, and maintaining engineering quality across all four engineering roles on the team
• Partner with other Engineers on novel simulation challenges, bring independent judgment to architectural tradeoffs, and shape the technical roadmap
• Mentor engineers on the team, raising the bar on systems design, kernel-level debugging, and engineering rigor
• Collaborate with adjacent platform teams on the operational model for a long-lived, multi-tenant service serving active cyber range deployments

Our Tech Stack:

Typescript, React, Postgres, Kotlin, Kubernetes, Spring Boot

What are the qualifications to apply? To be successful as a Senior Software Engineer, Network Simulation you need to have:

• Deep expertise in Linux kernel networking and eBPF program development, including XDP, TC hooks, BPF map types, and the tradeoffs involved in kernel-space packet processing
• Strong systems programming skills - C or Rust for eBPF program development, and Go or Python for the control-plane agent and tooling layer
• Solid understanding of real-world internet routing - BGP, ASN topology, CIDR allocation, inter-AS peering - sufficient to model it faithfully without running routing software
• Experience designing systems with well-defined control plane and data plane separation, particularly where distributed components may have intermittent connectivity to a central controller
• Demonstrated technical leadership: you have set architectural direction and driven engineering quality across a team, whether as a tech lead, principal, or senior-plus individual contributor
• Comfort at the intersection of research and production engineering - this role involves taking a proof of concept and building it into something that runs reliably at scale
• Familiarity with Kubernetes as the deployment environment for both control plane services and distributed agent components
• Experience with network simulation, traffic shaping, or cyber range infrastructure is a strong plus
• Prior work in cybersecurity, defense, or government-adjacent environments is a plus due to SimSpace's customer base

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

• Compensation. Base salary range: $160,000 - $225,000, reflecting our confidence in your expertise and impact, with the opportunity for annual bonuses tied to company performance and individual contributions.
• Health & Wellness. Comprehensive medical, dental, and vision benefits, plus savings plans-coverage starts on day one!
• Mental Health Support. Access to company-paid counseling, coaching, and resources for you and your family through Spring Health.
• Financial Well-Being. Plan for your future with a 401(k)-retirement savings plan featuring a company match.
• Flexible Time Off. Take the time you need with unlimited vacation and dedicated health & wellness days. SimSpace provides flexible solutions to meet the diverse work-life needs of team members.
• 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.
• Referral Rewards: Earn $1,500-$3,500 for every qualified hire through our employee referral program.
• Peloton Interactive Wellness Program: Full- and partial- subsidized membership plans and equipment discounts to help you reach your personalized fitness goals.
• 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.
• Extra Perks: Legal plan coverage, pet insurance, wellness reimbursements, and more to simplify life's details.