Junior Developer jobs in London

At CGI, you'll help deliver secure, high-impact solutions that enable government agencies to tackle some of their most complex and mission-critical challenges. As a Python Software Engineer, you'll work with modern technologies to build secure, scalable and reliable systems that drive real-world outcomes. You'll collaborate with talented colleagues, contribute innovative ideas, and take ownership of technical solutions in an environment that values continuous learning, creativity and professional growth. If you're passionate about solving complex engineering problems and want to make a meaningful impact while developing your career, CGI offers the opportunity to do just that.

CGI was recognised in the Sunday Times Best Places to Work List 2025 and has been named a UK ‘Best Employer’ by the Financial Times. We offer a competitive salary, excellent pension, private healthcare, plus a share scheme (3.5% + 3.5% matching) which makes you a CGI Partner not just an employee. We are committed to inclusivity, building a genuinely diverse community of tech talent and inspiring everyone to pursue careers in our sector, including our Armed Forces, and are proud to hold a Gold Award in recognition of our support of the Armed Forces Corporate Covenant. Join us and you’ll be part of an open, friendly community of experts. We’ll train and support you in taking your career wherever you want it to go.

Due to the secure nature of the programme, you will need to hold UK Security Clearance or be eligible to go through this clearance. This is role is required on a secure site.

Your future duties and responsibilities

In this role, you will develop secure, scalable Python applications that support mission-critical programmes within CGI's Space, Defence and Intelligence business. Working as part of a collaborative, cross-functional engineering team, you will design, build, test and enhance software solutions using modern development practices, while contributing ideas that help solve complex technical challenges. You'll take ownership of your work, share your expertise by mentoring colleagues, and play a key role in delivering high-quality solutions that make a tangible impact for our clients.

You'll also contribute to the continuous improvement of engineering standards, helping to evolve development processes, adopt new technologies and maintain a strong focus on quality, security and innovation throughout the software lifecycle.

Key responsibilities:

~Develop & Deliver secure, scalable Python software using modern engineering practices.
~Design & Document technical solutions and software components.
~Build & Maintain data processing pipelines for complex applications.
~Test & Assure quality through unit, integration and end-to-end testing.
~Collaborate & Mentor within cross-functional Agile delivery teams.
~Optimise & Improve development processes using DevOps and CI/CD practices.
~Innovate & Solve complex technical challenges with creative engineering approaches.
~Support & Enhance cloud-based and virtualised environments where appropriate.

Required qualifications to be successful in this role

You'll be an experienced Python Software Engineer with a passion for developing high-quality software and solving challenging technical problems. You will be comfortable working within collaborative delivery teams, have strong communication skills, and enjoy continuously learning new technologies. Experience across modern software engineering, testing and cloud-based environments will enable you to succeed in this role.

Essential qualifications:

~You should have at least five years' experience developing software using Python, including object-oriented and functional programming.
~Strong experience working within cross-functional software development teams.
~Proven ability to mentor and support junior engineers.
~Experience with unit, integration and end-to-end testing, with a quality-first mindset.
~Experience producing technical designs and documentation.
~Experience developing or maintaining data processing pipelines.
~Working knowledge of DevOps practices and cloud or virtualisation platforms.
~Strong interpersonal and stakeholder communication skills.
~Demonstrable enthusiasm for learning new technologies and driving innovation.

Desirable:

~Experience with AWS.
~Experience using Elasticsearch and Kibana.
~Containerisation experience with Docker, Kubernetes and/or OpenShift.
~Knowledge of security technologies and protocols, including PKI and TLS.

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Together, as owners, let’s turn meaningful insights into action.

Life at CGI is rooted in ownership, teamwork, respect and belonging. Here, you’ll reach your full potential because…

You are invited to be an owner from day 1 as we work together to bring our Dream to life. That’s why we call ourselves CGI Partners rather than employees. We benefit from our collective success and actively shape our company’s strategy and direction.

Your work creates value. You’ll develop innovative solutions and build relationships with teammates and clients while accessing global capabilities to scale your ideas, embrace new opportunities, and benefit from expansive industry and technology expertise.

You’ll shape your career by joining a company built to grow and last. You’ll be supported by leaders who care about your health and well-being and provide you with opportunities to deepen your skills and broaden your horizons.

That same commitment to fairness extends to how we use technology. To support our recruitment team, AI tools may be used to help assess applications though they never replace human judgement. All hiring decisions remain entirely in the hands of our recruitment professionals.

Come join our team—one of the largest IT and business consulting services firms in the world.