Senior Data Engineer (Data and AI)

About the role

You'll design and deliver the data pipelines, platforms and AI applications that drive our clients' decision-making, working directly with them to turn business questions into production-ready systems on Google Cloud. Our clients span different industries and sizes, from some of the world's biggest brands to fast-growing smaller businesses.

We give engineers real technical ownership. You'll be the technical lead on your own projects and client accounts, trusted to make the calls and own the outcome. You'll also be part of an engineering team that reviews each other's work and pitches in across projects. On your accounts, you'll work day to day with fifty-five's consultants and data scientists.

You'll combine strong SQL, Python and cloud engineering with sound technical judgement, using AI tools to build faster and to a higher standard while keeping full ownership of what you deliver. You'll also build AI applications for clients and for fifty-five's own teams, and help shape what we offer in data and AI.

What you'll do

• Design, build and operate scalable data pipelines, data models and end-to-end solution architectures on GCP (BigQuery, Python, dbt, Airflow, Dataform), balancing reliability, maintainability, performance and cost.
• Own technical delivery on your projects and accounts, from scoping to production: making the design decisions, managing risks and dependencies, and communicating trade-offs clearly.
• Own the quality of what we deliver, with rigorous validation, automated testing, observability and data-quality controls built into production pipelines, and lead the diagnosis and fix when production issues come up.
• Design and build AI applications for clients and for fifty-five, such as LLM agents on Google Cloud with Gemini and Google's ADK. Take them from prototype to production, with evaluation, cost control and secure handling of client data.
• Use agentic coding tools such as Claude Code or Codex to build faster and improve testing, checking their output critically and staying accountable for the result. Share what works with the team as demos, docs and reusable patterns.
• Work with clients, consulting and data science teams to clarify requirements, challenge assumptions and turn business needs into pragmatic designs, and explain your reasoning to technical and non-technical people.
• Raise the team's engineering standards through design and code reviews, strong testing practices and clear documentation.

What you'll bring

• Excellent SQL and strong Python skills.
• Proven experience designing, building and operating reliable data pipelines, data models and cloud platforms (GCP preferred, AWS or Azure also welcome), with transformation and orchestration tooling such as dbt, Airflow or Dataform.
• Strong software engineering practices: Git-based workflows, code review, automated testing and CI/CD.
• Hands-on experience building with LLMs (Gemini or similar), such as agents, connecting models to data and APIs, and evaluating outputs. The judgement to know when to rely on AI-assisted engineering tools and when to verify.
• The ability to break down ambiguous problems, see the business challenge behind a task, make well-reasoned decisions, and prototype and pitch ideas for what we could build for clients.
• Excellent client-facing communication and confidence leading delivery independently: running several client projects at once and re-prioritising as client needs change, solo or within a larger project team.

Desirable experience

• Infrastructure as code (Terraform), cloud IAM, and secure handling of client data.
• Taking LLM agents to production: evaluation and guardrails, cost control, or making them available in Slack, Teams or similar tools.
• Applied data science (exploratory or statistical analysis), and dashboarding tools such as Looker or Power BI.
• Marketing platforms and an understanding of marketing data.

About the company

Part of The Brandtech Group, fifty-five is a data company helping brands collect, analyse and activate their data across paid, earned and owned channels to increase their marketing ROI and improve customer acquisition and retention.

Headquartered in Paris with offices in London, Hong Kong, New York and Shanghai, fifty-five is a certified Google Partner company and was named by Deloitte as one of the fastest-growing tech firms in Europe, thanks to its unique technology approach combining talent with software and service expertise.

If this sounds like you, please get in touch! We look forward to meeting you.

In return, we are pleased to offer you the following benefits:

• Being part of a multicultural, dynamic and fast-growing team
• Continuous (and certified) training on the digital ecosystem and technologies (initial training for all new employees, followed by recurring training sessions)
• Private medical coverage through AXA
• Transport for London monthly travel card allowance
• The flexibility to work remotely for part of the week
• 25 days holiday per year, in addition to UK bank and public holidays
• Company pension plan
• Company-sponsored sporting and social activities
• Monthly Codecademy subscription - reimbursable upon completion of chosen training path

fifty-five encourages diversity and is committed to guaranteeing equal treatment of all applications, regardless of gender, age, origin, sexual orientation, state of health or political or religious opinion.