Senior Software Engineer

Zaizi; Greater London; Hybrid; GBP 90,000 - 130,000; Full time

Benefits offered by this job

Competitive pay

Job summary

Zaizi in the United Kingdom is seeking a Senior Full Stack & Systems Engineer to join our Defence delivery team, building mission-critical web applications and API backends for central MoD programmes.

You will span front-end, back-end and edge integration, ensuring Secure by Design and safety boundaries, while mentoring engineers and delivering funded MoD statements of work.

Qualifications

• Active UK security clearance (min) with UK nationality/sovereignty requirements.
• Hands-on experience delivering MoD software and SbD frameworks.
• 4+ years production experience with modern web stacks (TypeScript/React/Node.js or Python/FastAPI).
• Strong API design (REST/GraphQL/gRPC/WebSocket) and database design (PostgreSQL/SQLite).
• Proficiency in Kotlin or Java on native Android environments; IPC/AIDL knowledge.

Responsibilities

• Design and build secure web applications, microservices, and APIs for cloud and hybrid MoD landing zones.
• Develop native Android background services and IPC interfaces to connect front-end displays to back-end services.
• Implement SbD practices and cloud security guidance across CI/CD pipelines and environments.
• Lead technical user stories on funded MoD SoWs and mentor mid-level engineers.

Skills

TypeScript

React

Node.js

Python

Kotlin

Java

API design

CI/CD

DevSecOps

Tools

Docker

GitLab CI

GitHub Actions

K3s

Podman

Job description

We are seeking a Senior Full Stack & Systems Engineer to join our Defence delivery team. This is a versatile, high-impact role designed for funded client delivery: you will build mission-critical web applications and API backends for central MoD programmes, while contributing to low-level system integrations (Kotlin, Android ART, IPC/AIDL) on tactical edge and Situational Awareness (TAK) platforms.

You will sit at the intersection of modern enterprise software engineering and tactical edge integration, ensuring all code meets MoD Secure by Design (SbD) principles and Def Stan 00-056 safety boundaries.

• Full-Stack Application Development: Design and build resilient, secure web applications, microservices, and APIs (TypeScript, Node.js, React, or Python) for cloud and hybrid MoD landing zones.
• Edge & Tactical Systems Integration: Develop native Android background services (Kotlin on ART), IPC/AIDL interfaces, and Cursor-on-Target (CoT) data routers connecting front-end C2 displays (e.g., OmniTAK, ATAK) to backend services.
• Secure by Design (SbD) Implementation: Write clean, well-tested code following NCSC Secure Development Principles, NCSC Cloud Security Guidance, and JSP 440 controls.
• CI/CD & DevSecOps: Automate build, test, and containerisation pipelines (Docker, GitOps, GitLab CI/GitHub Actions) for both air-gapped systems and enterprise cloud environments.
• Client Delivery & Mentorship: Lead technical user stories on funded MoD statements of work (SoWs), participate in Agile delivery ceremonies, and mentor mid-level engineers.

Required Qualifications & Experience

Defence & Security Baseline

• Active UK SC Clearance (minimum) with UK nationality/sovereignty requirements.
• Hands-on experience delivering under MoD software development standards and Secure by Design (SbD) frameworks.

Full-Stack Engineering (Web & APIs)

• 4+ years of production experience with modern Web stacks (TypeScript, React, Node.js, or Python/FastAPI).
• Strong API design experience (REST, GraphQL, gRPC, WebSocket) and relational/non-relational database design (PostgreSQL, SQLite).

Systems & Mobile Architecture (Android ART)

• Proficiency in Kotlin or Java on native Android environments, including background services, thread management, and Inter-Process Communication (IPC via AIDL/Binders).
• Understanding of event-driven architectures, local socket communication, and memory optimization under resource-constrained conditions.

Desirable / Bonus Qualifications

• Experience with tactical mapping frameworks (TAK/ATAK, WinTAK, OmniTAK) or military telemetry protocols (Cursor-on-Target / CoT, STANAG 4586).
• Familiarity with containerisation at the edge (K3s, Podman) or local database layers (Room, RocksDB).
• Knowledge of Defence safety standards (Def Stan 00-056 / 00-055) and ALARP risk management.

• Competitive Pay:Salaries reviewed annually to ensure they reflect your performance and market value.
• Loyalty Pension:We invest in your future. Starting at a 5% employer contribution, we increase this by 0.5% every year after your third anniversary, up to amaximum of 8%.
• Protection:Comprehensive Group Life Assurance for peace of mind.

Purpose & Culture

• Real Impact:Work on mission-critical projects that secure and improve the UK's digital infrastructure.
• Autonomy:A culture that empowers you to make decisions, prototype rapidly, and iterate towards success.
• Service & Community:We support those who serve.10 paid daysfor Reservist Military Service.

Work / Life Balance

• Time Off:25 days annual leave+ Bank Holidays, with the flexibility to Buy/Sell additional days to suit your lifestyle.
• Giving back:2 paid volunteering days per year.

Development & Growth

• Master Your Craft:Fully funded professional certifications (AWS, GCP, Agile, etc.) supported by5 days paid study leave.
• Expand Your Horizons:An additional £500 annual "Personal Choice" fund to learn whatever inspires you - work-related or not.
• Support:Access to 1-2-1 professional coaching and team training to accelerate your career.

Health & Balance

• Premium Health:Vitality Private Medical Insurance (includes Apple Watch, gym discounts, and rewards).
• Flexibility:Genuine hybrid working with a WFH equipment allowance to perfect your home setup.

• Wellbeing:Cycle to Work scheme and a commitment to sustainable, healthy working practices.