Principal Backend Engineer in London

Publicis Media harnesses the power of modern media through leading agency brands Dysrupt, Infinite Roar, Publicis Collective, Publicis Health Media, Spark Foundry, Starcom and Zenith, as well as global accelerator PMX; immersive experience group PMCI and access to integrated platform-based technologies and offerings from CJ, Epsilon and Influential. A key business solution of Publicis Groupe, Publicis Media’s digital-first, data-driven global solutions deliver client value and drive growth in a platform-powered world. It is present in over 100 countries with over 23,000 employees worldwide.

Performics is the Performance Centre of Excellence within Publicis Groupe, building technology, data and AI-driven marketing solutions for global brands. This Principal Backend Engineer role is a hands-on, principal-level individual contributor position shaping the backend and data foundation behind OneSuite, our unified marketing intelligence and automation platform. You’ll set technical direction across data products and platform integration, write production-grade Python, and lead high-impact architectural decisions that make complex marketing data dependable, secure and usable across clients. A key focus is enabling AI-assisted analyst workflows, including agents built with the Claude Agent SDK, so teams can answer questions, surface issues and act on campaign opportunities with confidence.

Responsibilities

• Own backend and data architecture across pipelines, connector systems, platform APIs, agent/tool runtimes, CLIs and downstream product surfaces.
• Define durable domain boundaries and data contracts between warehouse outputs, operational stores, platform APIs, agent tools and user workflows.
• Lead the evolution of Databricks medallion pipelines (ingestion, normalisation and curated outputs for analytics and product use cases).
• Improve data quality and governance: schema enforcement, lineage, documentation and lakehouse-to-operational-store sync for consumer-facing data.
• Architect Python backend services on AWS serverless paths, including authentication and tenant-scoped access patterns.
• Shape how capabilities are exposed through OneSuite (streaming workflows, tool permissions, MCP integrations and stable CLI/API/MCP contracts).
• Set engineering standards (testing, CI/CD, deployment safety, observability) and mentor senior engineers through reviews, pairing and clear written guidance.

Qualifications

• Demonstrable experience in senior backend, data platform or distributed systems engineering roles, with principal-level ownership across multiple services or teams.
• Expert Python backend engineering (API design, service boundaries, async/concurrent systems) plus strong SQL and modern testing practices.
• Hands-on Databricks / PySpark experience and lakehouse/medallion architecture (or equivalent large-scale data pipeline experience).
• Strong AWS serverless background (Lambda, API Gateway, S3, DynamoDB, IAM) with infrastructure-as-code (e.g., CloudFormation/SAM).
• Deep understanding of multi-tenant SaaS design, authN/authZ, tenant isolation, secrets management and operational security.
• Experience designing stable data contracts and CLI/API/MCP contracts, including schema evolution and consumer-facing data models.
• Proven technical leadership through mentoring, architecture decisions, code review and clear trade-off communication (without relying on direct authority).

Additional Information

Publicis Media offers a wide range of benefits to support our employees. Full details are shared when you join, but highlights include core benefits such as Pension, Life Assurance, and Private Medical cover, alongside enhanced policies like Reflection Days and Shared Parental Leave. You’ll also have access to a range of additional initiatives.

Publicis Groupe works primarily from the office or our clients' office four days per week. Publicis Media is an equal opportunities employer. We welcome and encourage applications from people of all backgrounds, and do not discriminate on the basis of race, ethnicity, nationality, religion or belief, disability, age, citizenship, relationship status, sexual orientation, gender identity, or any other protected characteristic. We are committed to providing a fair, accessible, and inclusive recruitment process. If you have any access needs - for example, related to disability, neurodivergence, or a health condition - please let us know. We’ll work with you to ensure the process works for you. Sharing this information will never impact your application. Guided by our values, we listen with empathy, uplift each other, take responsibility, and embrace change - building a culture where everyone feels seen, respected, and genuinely included.