Senior Software Engineer Ref. 3697

Job Description

Flexible working: we support a variety of flexible working arrangements including term time and part time hours (minimum three days per week), compressed working patterns and flexible start and finish times. Due to the sensitive nature of the role, remote, hybrid or home working opportunities are not available.

About us

MI5 keeps the country safe from serious threats like terrorism and attempts by states to harm the UK, its people and way of life. We carry out investigations by obtaining, analysing, and assessing intelligence, and then work with a range of partners including MI6 and GCHQ to disrupt these threats. Through our protective security arm, we provide advice and guidance to government, businesses and other organisations about how to keep themselves safe. A role in MI5 means you'll do unique and challenging work in a supportive and encouraging environment, making a real difference to UK national security.

The role
As a Senior Software Engineer, you’ll help shape the future of our products, platforms and technical capability. You’ll explore emerging technologies, experiment with new approaches and validate ideas through rapid prototyping, before evolving the most promising concepts into secure, compliant and production-ready solutions.

Working within our Essential Technology team, you’ll contribute to organisation wide modernisation and tackle engineering problems you won’t find elsewhere. You’ll help steer MI5’s technical direction, ensuring our tools, platforms and services keep pace with fast moving challenges and opportunities. You’ll work closely with our Future Products and Technologies (CTO) team, to explore what’s possible, set technical direction and make architectural decisions that underpin future capability. Autonomy is a core part of the role: many briefs are intentionally broad, giving you freedom to investigate, experiment and determine the right approach.

Day to day, you’ll be hands on with cloud native architectures, container platforms like Docker and Kubernetes, hyperscale cloud services (particularly Amazon Web Services), the Model Context Protocol and modern Generative AI models. You might build platforms that analyse complex data at scale, create compliance services that ensure lawful and secure operation or develop internal tools that improve the developer experience. Whatever you’re working on, your solutions will be secure by design, resilient, observable and built to last.

You’ll provide leadership through tasking: running stand‑ups, coordinating sprints, breaking down work and supporting more junior engineers, while influencing senior stakeholders on feasibility, constraints and trade‑offs. This is a role with plenty of autonomy and opportunities to solve complex engineering problems you simply won’t find elsewhere.

About you

You’re a technologist who enjoys exploring new ideas and knows how to turn promising prototypes into robust, scalable, production‑ready systems. You’ve worked in a lead software engineering role within an agile environment, shaping architecture, setting technical direction and taking ownership of delivery. You don’t need formal line management experience; what matters is that you’ve influenced others, delegated or tasked work, and supported teams to build secure, resilient solutions.

You bring strong, practical, engineering capability, proficient in at least one modern language such as Java, C#, Python or JavaScript. You understand contemporary architectures such as microservices, Application Programming Interface (API)-first design and distributed systems, and you have essential experience with Docker and Kubernetes. You know how to build systems that are observable, resilient and secure‑by‑default, and you’re confident applying design patterns and secure‑by‑design principles to real‑world engineering problems.

Curious, open‑minded and highly practical, you thrive in environments where experimentation is encouraged and modernisation is constant. You’re comfortable working with loose briefs, shaping ambiguity into clear technical direction and making decisions that balance innovation with compliance, cost and long‑term maintainability.

Influencing others is one of your core strengths. You can explain technical trade‑offs clearly, help senior stakeholders understand feasibility and constraints, and guide more junior engineers by showing them not just what to build, but why it matters. Collaboration is another strength: you can work effectively with Product, Design, Data Science, Machine Learning (ML) and Cyber Security teams, shaping solutions that deliver end‑to‑end value.

Training and development

We’re committed to helping you grow your technical capability, leadership confidence and long‑term career. We use the Government Digital and Data Profession Capability Framework (GDDPCF) to provide clear expectations, structured pathways and the tools to deepen or broaden your expertise.

You’ll have opportunities to pursue specialist training and gain recognised qualifications across areas such as cloud engineering, AI/ML technologies, software architecture and security engineering. You’ll have access to coaching and mentoring, tailored development plans and internal/external training aligned to your goals. You’ll also be encouraged to take part in hackathons and spend up to 20% of your time on innovation and personal development. You could experiment with new frameworks, explore emerging technologies or contribute to engineering guilds and community initiatives.

You’ll also benefit from our capability‑based pay approach for GDDPCF roles, which recognises and rewards specialist technical expertise. Each grade includes three capability‑aligned pay points, and as you develop, maintain and evidence your technical skills, you’ll have the opportunity to progress through those levels. If you choose to move into line management, opportunities will be available, but they’re not a requirement: technical specialists can progress just as far through expert-level contribution.

From day one, you’ll have a buddy to help you settle in, support from your line manager and peers, and access to a thriving engineering community that values innovation, collaboration and continuous improvement. You’ll have autonomy, trust and the space to shape MI5’s next‑generation technologies, all while continuing to learn and grow in a role where the impact of your work truly matters.

Rewards and benefits

You’ll receive a starting salary of £79,969 plus other benefits including:

• 25 Days Annual Leave automatically rising to 30 days after 5 years' service, and an additional 10.5 days public and privilege holidays
• opportunities to be recognised through our employee performance scheme
• interest-free season ticket loan
• dedicated development budget
• excellent pension scheme
• cycle to work scheme
• facilities such as a gym, restaurant, and on-site coffee bars (at some locations)
• paid parental and adoption leave

Equal opportunities

At MI5 diversity and inclusion are critical to our mission. To protect the UK, we need a truly diverse workforce that reflects the society we serve. This includes diversity in every sense of the word: those with different backgrounds, ages, ethnicities, gender identities, sexual orientations, ways of thinking and those with disabilities or neurodivergent conditions. We therefore welcome and encourage applications from everyone, including those from groups that are under-represented in our workforce such as women, those from an ethnic minority background, people with disabilities and those from low socio-economic backgrounds.

Find out more about our culture, working environment and diversity on our website.

We’re disability confident

MI5 is proud to have achieved Leader status within the Department for Work and Pensions Disability Confident scheme. This is aimed at encouraging employers to think differently about disability and take action to improve how they recruit, retain, and develop disabled people. Being Disability Confident, we aim to offer a fair and proportionate number of person-to-person interviews to any candidate who self-identifies as disabled and meets the essential criteria for the role. This is our ‘Offer of Interview’ (OOI). To secure an interview for this vacancy, the essential criteria (in order of application process) are:

• you will be required to reach the minimum pass mark for the Organisational Situational Judgement Test which looks at your ability to problem solve. If you meet this criteria, you will be directed to complete an application form
• demonstrable ability in developing software in one common language (assessed at application form sift)
• demonstrable ability in taking a lead across multiple teams or taking responsibility for a particular technology specialism in a relevant role. As well as guiding and supporting less experienced individuals (assessed at application form sift)
• demonstrable proficiency in the use of the agile methodology and awareness of design patterns and how to implement them appropriately with security in mind (assessed at application form sift)
• demonstrable understanding of the principles of modern standards approaches such as continuous integration and delivery, test driven development and cloud services (assessed at application form sift)

There is a wide range of extra support available throughout the recruitment process to enable you to do your best, visit our how to apply page for information on reasonable adjustments we can offer.

What to expect

Our recruitment process is fair, transparent, and based on merit. Here is a brief overview of each stage, in order:

1. An initial online application form including pre-screening questions to ensure you meet our eligibility criteria
2. Online Situational Judgement Test (SJT) rating the appropriateness of your responses to a series of short scenarios. The SJT tests criteria important for all roles in our organisation
3. Application sift, looking at your motivation and skills for the role and the organisation. There will also be a competency question.
4. A technical, skill-based interview, based on the Government Digital and Data Profession capability framework.
5. If successful, you will receive a conditional offer of employment.

Please note, you must successfully pass each stage of the process to progress to the next. Your application may take around 6 to 9 months to process including vetting, so we advise you continue any current employment until you have received your final job offer.

Before you apply

To work at MI5, you need to be a British citizen or hold dual British nationality. Read about our eligibility criteria.

This role requires the highest security clearance, known as Developed Vetting (DV). It’s something everyone in the UK Intelligence Community undertakes. Find out more about the vetting process.

Please note we have a strict drugs policy, so once you start your application, you can’t take any recreational drugs and you’ll need to declare your previous drug usage at the relevant stage.

Before you apply, we advise you to consider setting up a separate email address for your contact with us, to ensure your personal and application correspondence remain separate. Try to avoid having identifying features in your email address, such as your first and/or surname and date of birth. This is good practise and will help you manage your application with us more discretely.

The role is based in Central London so you’ll need to live within a commutable distance. Please consider any financial implications and practicalities before submitting an application, as we do not offer relocation costs.

We offer reasonable reimbursement of travel costs for candidates attending in‑person interviews or assessments during the recruitment and vetting process. Full details will be provided with your interview or assessment invitation.

Reimbursement is discretionary and will only be made in line with the Candidate Expenses Policy, as amended from time to time. Candidates must book their own travel, using the most economical option, and provide original hardcopy receipts for reimbursement.

Please note, you should only launch your application from within the UK. If you are based overseas, you should wait until you visit the UK to launch an application. Applying from outside the UK will impact on our ability to progress your application. You should not discuss your application, other than with your partner or a close family member.

Right to withdraw statement:

Please be aware that we reserve the right to bring forward the closing date for this role from the original closing date once a certain number of applications have been received. Please be mindful of this and submit your application at your earliest convenience to avoid disappointment.