Rust Systems & Cross-Domain Software Engineer

ByDesign Secure Systems Ltd; West of England; Hybrid; GBP 90,000 - 120,000; Full time

Job summary

ByDesign Secure Systems Ltd is hiring a Rust Systems & Cross-Domain Software Engineer to build secure, mission-critical systems for UK government initiatives. You will work on a multi-year transformation program, delivering high-assurance software in air-gapped and security-sensitive environments.

The role requires active SC/DV clearance (or eligibility), UK citizenship, and experience with low-level Rust and cross-domain data transfer architectures. Hybrid work in the UK is possible.

Qualifications

• 4+ years low-level systems programming.
• 2+ years production Rust experience.
• Experience in air-gapped or offline environments.
• UK citizenship and active SC/DV clearance, or eligible.

Responsibilities

• Develop low-level cross-domain flow logic and endpoint daemons in Rust.
• Interface Rust software with COTS CDS APIs and message queues.
• Design memory-safe cross-domain data transfer daemons and flow controllers.
• Create hardware integration utilities and lightweight security agents.
• Produce and maintain technical designs and runbooks per standards.
• Operate solutions in air-gapped, security-sensitive environments.

Skills

Rust

Low-level systems programming

Strong communicator

Regulated security environments

Tools

COTS CDS APIs

Linux systems programming

Job description

Rust Systems & Cross-Domain Software Engineer

This role is delivered within secure environments. Candidates must hold active SC/DV clearance and hold UK citizenship.

Join the Mission

At ByDesign Secure, we believe that world-class security shouldn't be an afterthought—it should be the foundation. We are an independent, outputs-based consultancy dedicated to solving the most complex data assurance challenges in the UK public sector. Currently, we working on a landmark transformation of a cross-government secure IT system. This is an exciting opportunity to help engineer a private cloud environment from the ground up and modernize the end-user services that power national decision-making. We don't believe in \"billing by the hour\" or rigid hierarchies; we are a lean, expert team focused on delivering high-impact technical outcomes. If you are a self-starter who thrives on autonomy and wants to see your engineering or architectural decisions shape the future of sovereign security, we want to talk to you.

About the Opportunity

Are you a Rust Systems & Cross-Domain Software Engineer with a passion for engineering secure, mission-critical systems?

We’re looking for an experienced Rust Systems & Cross-Domain Software Engineer to join our team. You’ll be part of a multi-year transformation programme, shaping and implementing some of the most strategically significant government systems in operation today.

What You’ll Be Doing

Low-level software developer building custom high-assurance cross-domain flow logic, API connectors, and lightweight endpoint daemons in Rust.

Design and write memory-safe custom cross-domain data transfer daemons and flow controllers in Rust.

Develop lightweight endpoint security agents and custom hardware integration utilities.

Interface custom Rust software flows with COTS cross-domain appliance APIs and message queues.

Provide support to a model office environment where we will have the capability to demonstrate capabilities to our end users to facilitate rapid feedback.

Operate and maintain solutions within disconnected, air-gapped, and security-sensitive environments, ensuring compliance with organisational security requirements.

Collaborate with architecture, security, and engineering teams to deliver solutions aligned with enterprise standards and best practices.

Develop and maintain technical documentation, including High-Level Designs (HLDs), Component-Level Designs (CLDs), Low-Level Designs (LLDs), operational procedures, and support runbooks.

Produce and present technical designs, implementation plans, and service improvements through governance and Technical Design Authority (TDA) processes as required.

What You’ll Bring

4+ Years Low-Level Systems Programming with 2+ years production Rust experience.

Practical hands‑on knowledge of key technologies including: Rust (async/tokio, low-level IPC), Memory Safety Architecture, Linux Systems Programming, COTS CDS APIs.

Experience working in environments without direct internet connectivity.

Confident working within highly regulated or classified environments where reliability and compliance are paramount.

Strong communicator — able to bridge technical and non-technical stakeholders effectively.

Good standard of written communication to enable high-quality design outputs to be produced.

Bonus Points For

Prior experience working on government classified systems or within secure data centre environments.

Experience of configuring and using AI technologies within cloud environments.

Familiarity with NCSC guidance, UK Government cloud policies, or cross-domain architectures.

Cloud Certifications.

Existing DV clearance.

Why This Role?

Work on high-impact, nationally significant projects that make a real difference.

Join a trusted specialist integrator with a proven record of secure delivery into UK Government.

Be part of a multi-year programme offering long-term stability and genuine career growth.

Clearance Requirements:

This role requires either an existing Security Clearance (SC level) or for one to be passed before commencement. There must be a willingness to undergo Developed Vetting (DV).

Work Location: Hybrid remote in London / Bristol

Job Types: Temporary, Fixed term contract (outside of IR35)

Screener Questions:

Do you hold UK nationality? (Required due to client security restrictions)

Do you currently hold active UK SC clearance?

Are you eligible and willing to undergo UK SC/DV clearance for this role? (Applications without this cannot be considered)

Does your delivery approach allow for on-site presence in London or Bristol when required (typically 3 days per week)?