Join as Senior Windows Systems Developer

Kyber; United States; Hybrid; USD 150,000 - 210,000; Full time

Benefits offered by this job

Health insurance

50% transportation card reimbursement

Job summary

Kyber is seeking a senior Windows systems engineer to design, develop, and optimize low-level components—services, agents, and drivers—across user and kernel modes. You will work with native Win32 APIs and internal Windows ecosystem components, focusing on performance and security.

You will mentor juniors, participate in architecture decisions, and help evolve Windows internals tooling. The role offers on-site/hybrid/remote options across Europe, with French benefits and strong autonomy.

Qualifications

• 5–10 years of professional software development focused on Windows systems.
• Deep knowledge of Windows architecture, memory, synchronization, and error handling.
• Solid understanding of user-mode vs kernel-mode boundaries and session management.
• Hands-on experience with Windows debugging and analysis tools.
• Proficiency in C, C++, and Rust, plus x86/x64 assembly.

Responsibilities

• Design, develop, and optimize low-level Windows components (services, agents, drivers).
• Work with Win32 and NT Native APIs; integrate with Active Directory and Kerberos.
• Investigate performance, memory, synchronization, and security issues.
• Debug using crash dumps, kernel debugging, stack analysis, and reverse engineering.
• Contribute to architecture decisions; perform senior code reviews; write docs.
• Mentor junior engineers and maintain Windows internals tooling.

Skills

Windows systems

C/C++

Rust

Windows debugging

x86/x64 assembly

Visual Studio

Git workflows

Kernel-mode

Performance tuning

Tools

WinDbg

Windows Performance Analyzer

ETW

Job description

A senior engineer is needed to design, develop, and optimize low-level Windows system components for an open-source, ultra-low-latency remote-control platform. The work spans Windows services, system agents, and drivers, interacting with native APIs and the broader Windows ecosystem. The role is central to the platform's real-time performance goals and contributes to long-term low-level architecture decisions.

Responsibilities

• Design, develop, and optimize low-level Windows system components, including services, agents, and drivers in user-mode or kernel-mode as appropriate.
• Work directly with native Windows APIs such as Win32 and NT Native API, and integrate with Windows ecosystem components including Active Directory and Kerberos.
• Investigate and resolve complex issues related to performance, memory management, synchronization, and security.
• Perform advanced debugging, including crash dump analysis, kernel debugging, stack analysis, and occasional reverse engineering.
• Participate in low-level architecture decisions, conduct senior-level code reviews, and produce clear, durable technical documentation.
• Maintain a continuous technical watch on Windows internals and system-level tooling, and mentor junior engineers when appropriate.

Requirements

• 5 to 10 years of professional software development experience with a significant focus on Windows systems programming.
• Excellent knowledge of Windows internal architecture, including synchronization mechanisms, memory management, and system-level error handling.
• Clear understanding of user-mode versus kernel-mode boundaries and user session management.
• Hands-on experience with Windows debugging and analysis tools.
• Proficiency in C, C++, and Rust, plus working knowledge of x86/x64 assembly.
• Comfort with Visual Studio, the Windows toolchains, and Git-based collaborative workflows.
• Strong low-level reasoning, rigor, autonomy, attention to detail, and motivation to solve non-trivial technical problems.

Nice to have

• Experience in system security or Windows component hardening.
• Background in reverse engineering or malware analysis.
• Contributions to low-level or systems-oriented open-source projects.
• Experience in constrained environments such as real-time systems, high-availability setups, or security-critical software.

Benefits and work setup

• Full-time permanent contract based in Paris 13e, with on-site, hybrid, or full-remote options across Europe.
• Market-aligned salary plus typical French benefits including health insurance and 50% transportation card reimbursement.
• Strong autonomy in technical decision-making within a technically focused, intellectually challenging environment.