1. What is a Data Engineer at Barclays?

As a Data Engineer at Barclays, you are the foundational builder behind the bank’s ability to leverage data for critical financial services. You will design, build, and optimize the data architecture that powers everything from consumer banking analytics to complex risk modeling and regulatory reporting. Because financial institutions operate on trust and precision, your work ensures that data flows securely, accurately, and efficiently across the organization.

The impact of this position is massive. For example, Data Engineers working within the Mortgage Data domain process vast amounts of loan, customer, and market data to help the bank assess risk, predict market trends, and streamline the lending experience. Your pipelines directly influence the decisions made by quantitative analysts, product managers, and executive leadership. You are not just moving data; you are enabling a secure, data-driven financial ecosystem.

Expect a role that balances scale with rigorous regulatory complexity. Barclays handles petabytes of sensitive financial data, meaning you will face unique challenges around data governance, auditability, and high availability. Whether you are migrating legacy systems to modern cloud architectures or building real-time streaming pipelines for fraud detection, this role offers the opportunity to solve high-stakes engineering problems at an enterprise scale.

2. Common Interview Questions

The questions below represent patterns frequently seen in Barclays data engineering interviews. While you should not memorize answers, you should use these to practice structuring your thoughts, writing clean code on a whiteboard or shared screen, and refining your project narratives.

SQL and Data Manipulation

These questions test your ability to extract insights and transform data using advanced SQL features. Interviewers look for accuracy, edge-case handling, and performance awareness.

• Write a query to calculate the 7-day rolling average of daily transaction volumes.
• How would you identify duplicate records in a table without a primary key, and how would you delete them?
• Explain the difference between RANK(), DENSE_RANK(), and ROW_NUMBER().
• Given a table of employee salaries and departments, write a query to find the highest earner in each department.
• What is the difference between a LEFT JOIN and an INNER JOIN, and how do null values affect the outcome?

Programming and Pipeline Architecture

These questions evaluate your algorithmic thinking and your practical knowledge of building scalable data systems.

• How do you handle out-of-memory (OOM) errors in an Apache Spark application?
• Write a Python script to parse a large, deeply nested JSON file and flatten it into a tabular format.
• Describe the architecture of a pipeline that needs to ingest data from an API, transform it, and load it into a data warehouse daily.
• What are the trade-offs between storing data in Parquet versus CSV formats?
• How do you ensure data idempotency in a pipeline that runs multiple times a day?

Behavioral and Experience-Based

These questions form the core of the panel interview, assessing your culture fit, problem-solving methodology, and communication skills.

• Walk me through your resume, focusing specifically on your role in building the data architecture at your last company.
• Tell me about a time you identified a bottleneck in a system and how you resolved it.
• Describe a situation where you had to explain a complex technical data issue to a non-technical business stakeholder.
• How do you prioritize tasks when you receive urgent requests from multiple different teams simultaneously?
• Tell me about a project that failed or did not meet expectations. What went wrong, and what did you learn?

3. Getting Ready for Your Interviews

Approaching the Barclays interview process requires a strategic blend of technical review and reflective preparation. Interviewers want to see not only that you can write efficient code, but that you understand how your work fits into a heavily regulated, enterprise-level architecture.

Focus your preparation on the following key evaluation criteria:

Technical Execution & Fundamentals – You must demonstrate a strong command of data engineering core competencies, particularly SQL, Python or Scala, and distributed computing frameworks. Interviewers will evaluate your ability to write clean, optimized code and your understanding of how data is physically stored, partitioned, and processed at scale.

System Architecture & Data Modeling – This evaluates your ability to design robust data solutions from the ground up. You can demonstrate strength here by confidently discussing batch versus streaming architectures, data warehousing principles, and how you design schemas that balance query performance with storage costs.

Past Experience Deep-Dive – Interviewers at Barclays rely heavily on your previous work experience to gauge your technical depth. You will be evaluated on your ability to clearly articulate the business problem, the technical constraints, the architecture you chose, and the specific impact of your contributions to past projects.

Resilience and Culture Fit – Working in a global financial institution requires patience, strong stakeholder communication, and the ability to navigate ambiguity. Interviewers look for candidates who can collaborate effectively across technical and non-technical teams, manage shifting priorities, and uphold strict standards for data quality and security.

4. Interview Process Overview

The interview process for a Data Engineer at Barclays is designed to be thorough but accessible, focusing heavily on practical experience rather than obscure algorithmic puzzles. You will typically begin with a phone screen with a recruiter or hiring manager to align on your background, compensation expectations, and basic technical competencies. This is often followed by a technical screening round that assesses your foundational skills in SQL and data manipulation.

The core of the evaluation takes place during the panel interviews. Candidates often face a comprehensive 45-minute to 1-hour session that blends behavioral inquiries with deep technical questions based directly on your resume. Rather than abstract whiteboarding, interviewers prefer to anchor the technical discussion in systems you have actually built, probing your design choices, troubleshooting methods, and understanding of data pipelines.

While the technical difficulty is generally perceived as straightforward for well-prepared candidates, the process requires persistence. Barclays is a massive global organization, and administrative steps or internal reviews can sometimes stretch the timeline between stages. Candidates should approach the process with patience, maintain proactive communication with their recruiting contacts, and be prepared to clearly articulate the business value of their past engineering work.

This visual timeline outlines the typical progression from initial contact through the technical and panel stages to the final decision. Use this to pace your preparation, focusing first on core technical fundamentals before shifting your energy toward storytelling and deep-diving into your past project architectures for the panel rounds. Keep in mind that timelines can vary depending on the specific team, location, and seniority of the role.

5. Deep Dive into Evaluation Areas

To succeed, you must understand exactly what the interview panel is looking for across different technical and behavioral dimensions. Below are the core areas you will be evaluated on.

Data Modeling and SQL Proficiency

• This area is critical because SQL remains the primary language for data validation, transformation, and analysis at Barclays. Interviewers evaluate your ability to write complex, efficient queries and your understanding of how to structure data for different use cases. Strong performance looks like writing queries that handle edge cases seamlessly and explaining the performance implications of your joins and aggregations.
• Complex Joins and Window Functions – Expect to write queries that rank data, calculate running totals, or identify gaps in time-series data.
• Schema Design – You should be comfortable discussing Star and Snowflake schemas, normalization versus denormalization, and slowly changing dimensions (SCDs).
• Query Optimization – Be ready to explain how to read an execution plan, the importance of indexing, and how to resolve data skew in distributed databases.
• Advanced concepts (less common) – Query compilation phases, cost-based optimizers, and deep internals of specific database engines (e.g., PostgreSQL or Oracle).
• "Given a table of customer transactions, write a query to find the top three spending customers in each region for the last quarter."
• "How would you design a data model to track historical changes in mortgage interest rates over time?"
• "Explain a time you had to optimize a slow-running query in a production environment. What steps did you take?"

Data Pipeline and ETL/ELT Architecture

• Barclays relies on robust pipelines to move data from operational systems into analytical environments. This area tests your practical knowledge of extracting, transforming, and loading data reliably. Strong candidates can discuss the trade-offs between different batch and streaming tools and know how to build pipelines that are idempotent and fault-tolerant.
• Distributed Computing – A solid grasp of how frameworks like Apache Spark or Hadoop process data across clusters, including concepts like partitioning, shuffling, and lazy evaluation.
• Orchestration Tools – Understanding how to schedule and monitor workflows using tools like Apache Airflow, including handling dependencies and retries.
• Data Quality and Governance – Knowing how to implement checks within your pipeline to catch nulls, duplicates, or malformed data before it reaches downstream users.
• Advanced concepts (less common) – Exactly-once processing semantics in streaming, custom state management in Apache Flink, or deep Spark memory tuning.
• "Walk me through the architecture of the most complex data pipeline you have built. What tools did you use and why?"
• "How do you handle late-arriving data in a daily batch pipeline?"
• "Explain the difference between a broadcast join and a shuffle hash join in Spark."

Past Experience and Behavioral Fit

• Because the panel heavily indexes on your resume, this area evaluates your actual track record and how you operate within a team. Interviewers want to see that you take ownership of your work and can communicate technical concepts to non-technical stakeholders. A strong performance involves using the STAR method (Situation, Task, Action, Result) to provide concise, impactful narratives.
• Project Ownership – Discussing a project from inception to deployment, highlighting your specific contributions and architectural decisions.
• Conflict and Collaboration – Explaining how you navigate disagreements with product managers or other engineers regarding technical debt or deadlines.
• Navigating Constraints – Sharing examples of how you delivered value despite legacy system limitations, strict regulatory requirements, or tight timelines.
• "Tell me about a time you had to push back on a stakeholder's request because it wasn't technically feasible or secure."
• "Walk me through a production failure you experienced. How did you troubleshoot it, and what did you learn?"
• "Describe a situation where you had to learn a new technology quickly to deliver a project."

6. Key Responsibilities

As a Data Engineer at Barclays, your day-to-day work revolves around building and maintaining the infrastructure that makes data accessible and reliable. You will spend a significant portion of your time designing ETL/ELT pipelines that ingest data from various internal systems, third-party vendors, and legacy mainframes, transforming it into clean, usable formats stored in data lakes or warehouses.

Collaboration is a massive part of the role. You will work closely with quantitative analysts, data scientists, and risk managers to understand their data needs. For example, if you are working as a Mortgage Data Engineer, you will partner with domain experts to ensure that loan origination data is accurately modeled for downstream risk assessment and regulatory reporting. This requires not just writing code, but deeply understanding the financial context of the data you are moving.

Furthermore, you will be responsible for operational excellence. This means setting up monitoring and alerting for your pipelines, participating in code reviews, and ensuring that all data handling complies with strict banking regulations and internal governance policies. You will frequently optimize legacy processes, migrating on-premise workloads to modern cloud infrastructure while ensuring zero disruption to daily banking operations.

7. Role Requirements & Qualifications

To be competitive for a Data Engineer position at Barclays, you need a solid foundation in distributed systems, programming, and database management. The ideal candidate blends strong technical execution with an understanding of enterprise data governance.

• Must-have skills – Proficiency in at least one primary programming language (Python, Scala, or Java).
• Must-have skills – Expert-level SQL and experience with relational database management systems (RDBMS).
• Must-have skills – Hands-on experience with big data processing frameworks, particularly Apache Spark or Hadoop ecosystems.
• Must-have skills – Experience building and orchestrating data pipelines using tools like Apache Airflow or similar enterprise schedulers.
• Nice-to-have skills – Familiarity with cloud platforms (AWS, Azure, or GCP) and cloud-native data tools (e.g., Snowflake, Redshift).
• Nice-to-have skills – Domain knowledge in financial services, banking, or specifically mortgage data, which significantly reduces ramp-up time.
• Nice-to-have skills – Experience with CI/CD pipelines, infrastructure as code (Terraform), and containerization (Docker/Kubernetes).

For more senior positions, such as an AVP (Assistant Vice President) level, expectations shift heavily toward architectural leadership. You must demonstrate the ability to mentor junior engineers, lead complex cross-functional data initiatives, and make high-level design decisions that align with the bank's long-term technology strategy.

8. Frequently Asked Questions

Q: How difficult are the technical interviews for this role? Candidates generally rate the technical difficulty as accessible to moderate. Barclays is less interested in esoteric LeetCode hard problems and more focused on practical SQL, standard data manipulation in Python/Scala, and your ability to discuss real-world pipeline architectures.

Q: How long does the interview process typically take? The process can take anywhere from a few weeks to over a month. Administrative delays and scheduling challenges with panel members are common in large banks. It is highly recommended to follow up politely with your recruiter if you have not heard back after a week or two.

Q: What is the working culture like for a Data Engineer at Barclays? The culture is highly professional, structured, and risk-aware. Because you are dealing with financial data, there is a strong emphasis on accuracy, governance, and thorough documentation over moving fast and breaking things. Collaboration and clear communication are highly valued.

Q: Is financial domain knowledge required to get an offer? While not strictly required for most individual contributor roles, having a background in finance, banking, or specific domains like mortgage data is a massive advantage. If you lack this background, demonstrate a strong willingness to learn the business context behind the data.

Q: Does Barclays hire remotely or expect hybrid work? Barclays generally operates on a hybrid model, expecting employees to be in the office (such as the Whippany, NJ campus) a few days a week. Be sure to clarify the specific location and attendance expectations with your recruiter during the initial screen.

9. Other General Tips

• Drive the Resume Conversation: In your panel interview, you will be asked heavily about your past work. Take control of this narrative. Prepare 2-3 deep technical stories that highlight your architectural decisions, the scale of the data, and the business impact.
• Emphasize Data Quality: In a bank, bad data can lead to regulatory fines or poor risk models. Whenever discussing pipelines or SQL, proactively mention how you would implement data quality checks, logging, and error handling.

• Brush Up on the Fundamentals: Do not overcomplicate your preparation. Ensure your SQL window functions are flawless and that you can confidently explain the internal workings of the tools listed on your resume (e.g., Spark shuffling, Airflow DAGs).
• Ask Business-Centric Questions: At the end of your interviews, ask questions that show you care about the business. Ask about how the data team supports the mortgage division, what regulatory challenges they are currently facing, or how they measure the success of their data platform.

10. Summary & Next Steps

Preparing for a Data Engineer interview at Barclays is an opportunity to showcase your ability to build robust, scalable systems in a high-stakes financial environment. By focusing on core data engineering fundamentals—like advanced SQL, distributed computing concepts, and pipeline orchestration—you will be well-equipped to handle the technical assessments. More importantly, by refining the narratives around your past experiences, you will demonstrate the maturity and problem-solving mindset required to thrive in this highly regulated space.

The compensation data above reflects the typical range for this position, particularly at the AVP level. Keep in mind that total compensation in banking often includes a base salary alongside performance-based bonuses and comprehensive benefits, which you should discuss with your recruiter at the appropriate time.

Approach your preparation with confidence and structure. Review your past projects, practice articulating your design choices out loud, and remember that interviewers want to see how you think as much as what you know. For more granular insights, practice questions, and peer experiences, continue exploring resources on Dataford. You have the technical foundation to succeed—now focus on demonstrating your value clearly and confidently. Good luck!