Senior Developer - Python and Spark

Citi is looking for a Senior Data Engineer to design and build the next-generation data processing and analytics platform that sits at the core of our AI-driven business innovation. In this role, you will architect scalable ETL/ELT pipelines using Python and PySpark, while also integrating Generative AI and Machine Learning models to push the boundaries of what our data systems can do. Working within a high-performing engineering team, you will shape how data flows, performs, and delivers value across the organisation at scale.

Responsibilities

• Design and build highly scalable ETL/ELT pipelines in Python and PySpark to power reliable data ingestion, transformation, and integration at scale.

• Develop production-grade code and elevate team capability through structured code reviews and hands-on peer mentorship.

• Integrate Generative AI and Machine Learning models into data workflows, using AI development tools to deliver innovative solutions and resolve complex technical challenges.

• Establish and enforce data quality standards across all pipelines, ensuring accuracy, consistency, and reliability of data throughout its lifecycle.

• Implement an AI-first engineering approach by exploring and embedding Agentic AI workflows to increase development velocity and platform intelligence.

• Automate CI/CD pipelines for builds and deployments, advancing DevOps maturity across the data platform.

• Apply performance tuning and optimisation techniques to process large volumes of structured and semi-structured data efficiently and at speed.

• Collaborate directly with engineers and product owners to align technical direction with delivery goals and accelerate outcomes.

Required Qualifications & Skills

• Deep hands-on expertise in Python and Apache Spark, including Spark Core, Spark SQL, and DataFrames/Datasets, applied to production data systems.

• Advanced SQL capability across complex query writing, data transformation logic, and query performance optimisation.

• Demonstrated experience designing, building, and maintaining ETL/ELT pipelines for large-scale data ingestion and transformation.

• Proficiency with Python data processing libraries including Pandas, NumPy, and SciPy for data wrangling and preprocessing tasks.

• Practical experience with DevOps tools and CI/CD pipeline automation, with version control managed through GitHub.

• Solid working knowledge of Linux environments, with familiarity across Windows systems.

• Ability to collaborate across multidisciplinary teams to diagnose complex technical problems and deliver effective, lasting solutions.

Beneficial Skills & Qualifications

• Working knowledge of Machine Learning and Generative AI, with direct exposure to AI development tooling in an engineering context.

• Familiarity with Agentic AI workflows and their application to enhancing platform capabilities or development productivity.

• Experience using Jupyter Notebook for rapid prototyping and iterative development of data solutions.

What We Offer

At Citi, you will work on technically challenging problems that matter, contributing to a platform that shapes how a global financial institution processes and derives intelligence from data. This is a role where technical depth, curiosity, and engineering rigour are genuinely valued.

• Hybrid working model with 3 days in the office and 2 days working remotely, giving you flexibility and in-person collaboration.

• Access to complex, large-scale engineering challenges at the intersection of data and AI, keeping your technical skills at the forefront of the industry.

• Opportunities to grow into AI and platform architecture disciplines, supported by a team culture that invests in continuous technical development.

• Exposure to a globally connected engineering network, collaborating with specialists across technology, data, and product functions.

• A performance-driven environment where your contributions to platform innovation directly influence business outcomes at scale.

• Wellbeing and work-life balance support, alongside a competitive benefits package designed to recognise the value you bring.

Build data systems that power real decisions — apply now to join Citi's next-generation AI and data platform engineering team.