Kantar

We’re the world’s leading data, insights, and consulting company; we shape the brands of tomorrow by better understanding people everywhere.

Kantar’s Profiles division is home to the world’s largest audience network.

With access to 170m+ people in over 100 global markets, we offer unrivalled global reach with local relevancy. Validated by industry leading anti-fraud technology, Kantar’s Profiles Audience Network delivers the most meaningful data with consistency, accuracy, and accountability – all at speed and scale.

Job Details

We’re the world’s leading data, insights, and consulting company; we shape the brands of tomorrow by better understanding people everywhere.

About the job

We are looking for a Senior Backend Engineer to join our growing engineering team. In this role, you will work on both internal platforms and client‑facing services, building scalable, secure, and high‑performance backend systems that operate on a global scale!

You will primarily work with Python, FastAPI, and modern cloud‑native architectures, designing and developing APIs that sit in front of AI‑powered and data‑driven products.

A key part of the role will involve migrating data science and machine‑learning workloads into robust, maintainable, and engineering‑compliant services and infrastructure.

You will collaborate closely with data scientists, product managers, and other engineers to translate analytical and AI capabilities into reliable backend services. As a senior engineer, you will help shape technical direction, influence architectural decisions, and ensure that systems meet high standards for reliability, performance, and maintainability.

Job Goals

Backend Development

• Take technical ownership of one or more backend services, from design through to production and ongoing operation.
• Drive design and architecture decisions for backend services, balancing short‑term delivery with long‑term maintainability.
• Review and improve existing codebases, identifying opportunities for refactoring, simplification, and performance improvements.
• Set and promote best practices for Python service structure, dependency management, and API design.

Data & Persistence

• Ensure data consistency, reliability, and scalability across services.
• Design database schemas and write efficient queries aligned with application requirements.

AI & Platform Integrations

• Build backend support for AI‑powered features such as text analysis, classification, summarisation, or automation.
• Design scalable and observable integrations with external APIs and internal analytics systems.
• Collaborate with data science and product teams to operationalise advanced analytical and AI‑driven use cases.

Leadership & Team Contribution

• Mentor and support other engineers through code reviews, pairing, and technical guidance.
• Lead by example in writing clear, maintainable, and well‑tested code.
• Contribute to hiring activities such as technical interviews and onboarding of new engineers.
• Help shape team processes, ways of working, and technical standards.

Collaboration & Communication

• Contribute to technical design discussions and architecture decisions.
• Strong written and verbal communication skills for presenting findings to stakeholders.

Ideal Skills & Capabilities

Backend & Python Skills

• Deep understanding of Python internals, performance characteristics, and common pitfalls in production systems.
• Strong experience with async Python (e.g. asyncio, async FastAPI patterns) and knowing when not to use it.
• Experience structuring large Python codebases with clear boundaries, shared libraries, and versioning strategies.
• Proven ability to design testable, maintainable Python services, with a strong emphasis on automated testing and code quality.
• Experience evolving Python APIs and services without breaking downstream consumers.
• Practical experience managing Python projects with Poetry, including dependency resolution and packaging.

Platform Modernisation & Migration

• Lead and contribute to the migration of Python services from AWS Lambda to Kubernetes‑deployed applications.
• Evaluate existing Lambda‑based workloads and redesign them for long‑running, containerised services.
• Identify and address challenges related to configuration, scaling, observability, and cost when moving to Kubernetes.
• Work closely with platform and DevOps teams to define deployment patterns, health checks, and runtime standards for Python services in Kubernetes.

Databases & Infrastructure

• Experience working with PostgreSQL or other relational databases.
• Understanding of database migrations, indexing strategies, and query optimisation.
• Experience with CI/CD pipelines and DevOps tooling (e.g. GitHub Actions, Docker, Kubernetes).

Soft Skills

• Excellent problem-solving skills and attention to detail.
• A proactive mindset to identify and address potential issues or opportunities.

Nice‑to‑Have Skills

• Contribute to backend services written in NodeJS and TypeScript, supporting shared platforms and internal tooling.
• Confidently read, debug, and extend existing TypeScript codebases where required.
• Knowledge of event‑driven architectures and message queues (e.g. Kafka, RabbitMQ).
• Exposure to cloud platforms such as AWS, Azure, or GCP.
• Understanding of observability tools for logging, metrics, and tracing.

What’s in it for you

On top of all your normal benefits like holiday, meal cards and life assurance, we also offer:

• Five days of Life Leave per year; for those days when life just…gets in the way.
• Birthday leave – one extra day of holiday taken on the nearest workday to your birthday
• Two days a year to give back and volunteer with an organisation of your choice.
• Enhanced primary and secondary carer leave for however you choose to grow your family.
• The chance to hit the beach on your lunch break (yes, we have somewhere you can store your surfboard!)

Please be aware, the majority of our roles are hybrid, working three days a week in our office.

We’re not able to offer visa sponsorship or help with relocation support for this role. Please make sure you’ve got the right to work in the country where this role is located before applying.

What part of Kantar might I be joining?

You’ll be joining our Profiles division, home to specialists in survey design, sampling and data science. With the world’s largest audience network (over 170 million people), we’re trusted by many of the worlds leading brands to provide amazing insights from real people.

Some key facts:

• Our team is made up of 600 people globally.
• We are present in 27 countries.
• Profiles currently holds a 10% share in the $3b panel industry but we have ambition, a robust 3-year business plan and the financial backing of our private equity owners (Bain Capital) to grow to be the #1 player in this sector.
• We provide an ideal environment for professional growth, offering:
  • A ‘start-up’ atmosphere in which you can make a big impact and get credit for it.
  • The chance to learn all aspects of the business and influence the decision-making process.
  • The opportunity to network and learn from highly experienced, senior members of our teams from across the business, globally.

Why join Kantar?

We shape the brands of tomorrow by better understanding people everywhere. By understanding people, we can understand what drives their decisions, actions, and aspirations on a global scale. And if we combine the expertise of our people with the latest AI technology, we can really help brands discover some amazing insights.

And because we know people, we like to make sure our own people are being looked after as well. Equality of opportunity for everyone is our highest priority and we support our colleagues to work in a way works for them. We encourage applications from all backgrounds and sections of society. Even if you feel like you’re not an exact match, we’d love to receive your application and talk to you about this job or others at Kantar.

Privacy and Legal Statement

At Kantar, the diversity of our employees provides a richer environment for our employees and broader depth and breadth of thinking for our clients. Kantar is committed to inclusion and diversity; therefore, we welcome applications from all sections of society and do not discriminate based on age, race, religion, gender, pregnancy, sexual orientation, gender identity, disability, marital status, or any other legally protected characteristics.

PRIVACY DISCLOSURE: Please note that by applying to this opportunity you consent to the personal data you provide to us to be processed and retained by The Kantar Group Limited (“Kantar”). Your details will be kept on our Internal ATS (Applicant Tracking System) for as long as is necessary for the purposes of recruitment, which may include your details being shared with the hiring manager.

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Country

Portugal

Why join Kantar?

We shape the brands of tomorrow by better understanding people everywhere. By understanding people, we can understand what drives their decisions, actions, and aspirations on a global scale. And by amplifying our in-depth expertise of human understanding alongside ground-breaking technology, we can help brands find concrete insights that will help them succeed in our fast-paced, ever shifting world.

And because we know people, we like to make sure our own people are being looked after as well. Equality of opportunity for everyone is our highest priority and we support our colleagues to work in a way that supports their health and wellbeing. While we encourage teams to spend part of their working week in the office, we understand no one size fits all; our approach is flexible to ensure everybody feels included, accepted, and that we can win together. We’re dedicated to creating an inclusive culture and value the diversity of our people, clients, suppliers and communities, and we encourage applications from all backgrounds and sections of society. Even if you feel like you’re not an exact match, we’d love to receive your application and talk to you about this job or others at Kantar.

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