Principal Full Stack Engineer

Principal Full-Stack Software Engineer

Location: London
Employment Type: Permanent
Programme: Robert Walters Workforce Consultancy

About the Opportunity

Robert Walters is seeking an experienced Principal Full-Stack Software Engineer to join our Workforce Consultancy Programme, working on a long-term technology assignment with a leading organisation within the financial services sector.

Through our Workforce Consultancy Programme, you will be employed permanently by Robert Walters and deployed to work with one of our established client organisations. This provides the opportunity to contribute to significant technology initiatives while benefiting from permanent employment and ongoing support from Robert Walters.

This is a senior, hands-on engineering role for someone who can design, develop and operate production-grade software solutions across APIs, data products, enterprise integrations and AI-enabled tools.

You will combine deep technical expertise with engineering leadership, helping shape technical direction, establish best practices and deliver secure, scalable and reliable solutions in a regulated environment.

The Role

You will work across software engineering, data, integration and AI agent tooling, developing reusable technology that improves business workflows and enables applications and automated tools to access trusted business capabilities.

Key responsibilities will include:

• Designing, developing and maintaining production-grade software, with a strong focus on Python Back End engineering and API development.

• Building secure, reusable APIs and integration components to connect enterprise systems.

• Developing data products and pipelines to provide reliable, governed and reusable data services.

• Building tools that enable AI agents to retrieve information and execute defined workflows securely.

• Taking ownership of the full software development life cycle, including design, coding, testing, deployment, monitoring and ongoing production support.

• Establishing engineering standards across security, testing, observability, deployment and operational resilience.

• Providing technical direction, mentoring engineers and contributing to architectural and design reviews.

• Working collaboratively with product, architecture, data, security and business stakeholders to deliver effective solutions.

Essential Skills and Experience

• Extensive hands-on software engineering experience delivering and supporting production systems.

• Strong Python development skills, including building production services and APIs using FastAPI or a comparable framework.

• Strong understanding of API design, distributed systems, enterprise integrations, authentication and authorisation.

• Experience developing data pipelines and data products using SQL, Snowflake, dbt, Azure Data Factory or comparable technologies.

• Experience across the software development life cycle, including automated testing, deployment, observability and production support.

• Strong architectural judgement and the ability to balance delivery speed with security, resilience and maintainability.

• Experience providing technical leadership and mentoring while remaining actively involved in software development.

Desirable Skills

• Experience developing AI-enabled applications or agent-based solutions that interact with data, APIs and business workflows.

• Knowledge of event-driven architectures and batch processing.

• Experience implementing governance, auditability, permissions and failure-handling controls.

• Experience working within financial services, wealth management or another regulated environment.

• Ability to work across Back End services and user-facing components where required.

The Ideal Candidate

You will be a technically credible, hands-on Principal Engineer who enjoys solving complex engineering challenges and delivering working software into production.

You will be comfortable working across software, data and integration disciplines, influencing technical decisions across teams and helping other engineers develop their capabilities.

You will take ownership of engineering outcomes and understand the importance of building secure, reusable, reliable and supportable solutions.

Why Join Robert Walters Workforce Consultancy?

• Permanent employment: Join Robert Walters as a permanent employee rather than working on a traditional fixed-term contract.

• Leading client environments: Work on technology initiatives with established organisations across financial services, insurance and other sectors.

• Long-term career development: Build your technical experience through challenging assignments and exposure to enterprise technology environments.

• Ongoing support: Benefit from the support of Robert Walters throughout your consultancy assignment.

Apply Today

If you are an experienced software engineer looking to combine hands-on Python development, API engineering, data integration and technical leadership, we would welcome your application.

Join the Robert Walters Workforce Consultancy Programme and take the next step in your engineering career.

We are committed to creating an inclusive recruitment experience. If you require support or adjustments to the recruitment process, our Adjustment Concierge Service is here to help. Please feel free to contact us at (see below) to discuss how we can support you.

This position is being recruited on behalf of our client through our Outsourcing service line. Resource Solutions Limited, trading as Robert Walters, acts as an employment business and agency, partnering with top organizations to help them find the best talent. We welcome applications from all candidates and are committed to providing equal opportunities.