C++ Software Engineer (SC clearance - Inside IR35)

Onyx-Conseil; Cheltenham; On-site; GBP 65,000 - 90,000; Full time

Job summary

Onyx-Conseil is seeking a SC cleared C++ Software Engineer to join a busy team delivering projects across bare‑metal to large‑scale Android and Linux deployments. You will work across front‑end design and embedded platform development, leveraging strong C++ experience and a solid grounding in Python.

Familiarity with Kotlin, JavaScript and Rust is a plus. The role requires full‑time onsite work (minimum four days per week) and the ability to obtain a high level security clearance.

Qualifications

• Strong C++ experience and security clearance required.
• Onsite work four days per week; willing to obtain security clearance.

Responsibilities

• Designing a new clean‑slate product with complete autonomy over its architecture.
• Adding new capabilities to, or replacing a core component of, an existing product.
• Throwing together a quick‑and‑dirty prototype to confirm feasibility and iterating until it meets requirements.

Skills

C++

Python

C

Kotlin

JavaScript

Rust

Job description

Our Client are looking for a SC cleared C++ Software Engineer to join a busy team. The projects are typically focused on communications and analytics, targeting a variety of platforms from bare‑metal through to large‑scale Android and Linux deployments. We're looking for developers who thrive on diverse requirements, capable of jumping from front‑end design to embedded platform development throughout their working week.

It requires strong C++ experience and a solid grounding in Python, C, Kotlin, JavaScript and Rust would be beneficial. The team focuses on user‑driven applications, often involving bespoke hardware solutions. While not required, strong fundamentals in Radio Frequency (RF) communications and a desire to learn more will be an advantage.

Candidates must work full‑time onsite, a minimum of four days per week, and should possess or be willing to obtain a high level security clearance. Successful applicants will need to be security cleared prior to appointment, which can take a minimum of ten weeks.

Key Responsibilities

• Designing a new clean‑slate product with complete autonomy over its architecture.
• Adding new capabilities to, or replacing a core component of, an existing product.
• Throwing together a quick‑and‑dirty prototype to confirm the feasibility of a proposed technical approach; iterating until it meets requirements.

We are committed to fostering an inclusive, equitable and accessible workplace where everyone feels valued and supported. We welcome applications from all individuals, regardless of background or identity, and we encourage candidates who may not meet every listed requirement to still apply. If you require any adjustments or support during the recruitment process, please let us know and we will work with you to ensure a fair and accessible experience.