Tech Lead

WPP is the trusted growth partner for the world’s leading brands. We unite cutting-edge media intelligence and data solutions, world-class creativity, next-generation production, transformative enterprise solutions and expert strategic counsel in a single company – powered by exceptional talent and our agentic marketing platform, WPP Open, to help our clients navigate change, capture opportunity and deliver transformational growth. We work with the world's most valuable brands and have global reach across 100+ markets, with deep local expertise. Our people are the key to our success. We're committed to fostering a culture of creativity, belonging and continuous learning, attracting and developing the brightest talent, and providing exciting career opportunities that help our people grow. For more information, visit WPP.com. Minimum qualifications: • Bachelor's degree or equivalent practical experience. • 11 years of professional software development in Python, including 5 years of architecture across multiple systems. • 3 years of experience owning engineering standards adopted beyond your own team, and mentoring senior engineers. • Experience working in globally distributed teams across time zones, with engineering, product and business stakeholders in other regions. • Language and craft. You are an expert in Python. You write idiomatic, fully typed Python, understand asyncio and the GIL in depth, and can diagnose concurrency, CPU and memory problems in production. You set our Python version strategy, dependency policy, framework choices (FastAPI or Django) and coding patterns, and you are a practitioner in at least two other crafts. • APIs and data formats. You design REST APIs with OpenAPI from first principles: resource modelling, HTTP semantics, pagination, consistent error formats, versioning, idempotency and rate limiting. You know when to use JSON and when to use Protocol Buffers, and how to evolve both without breaking consumers. You set our API and serialisation standards and decide on exceptions. • Data. You are fluent in PostgreSQL, including schema design, indexing, query plans, transactions and zero-downtime migrations with SQLAlchemy and Alembic. You design DynamoDB and MongoDB models around access patterns, use Redis for caching, and choose the right store for each workload. You own our data-architecture standards, including how datastores are introduced and retired. • Asynchronous systems and reliability. You design event-driven systems on queues and streams such as SQS, Kafka and Celery or Arq, using retries, dead-letter queues and idempotent consumers so that at least-once delivery is safe. You know the outbox and saga patterns and when orchestration is better than choreography. You own our reference architecture for reliability. • Cloud and platform. You have built and run production services on AWS or GCP, both as Lambda functions and as Kubernetes workloads, and you understand the trade-offs between them: cold starts, concurrency, cost, capacity and deployment risk. You define infrastructure as code with Terraform or AWS CDK and release safely with canary and blue/green deployments. With Platform Engineering, you decide when we use serverless and when we use Kubernetes, and you set the reference architectures for both. • Testing and quality. You practise test-driven development and expect every team to do the same. You build balanced test suites: unit tests with pytest, integration tests with Testcontainers, contract tests with Pact, and Playwright end-to-end tests that gate releases. You set our quality standard and approve any exceptions to it. • Observability and performance. You instrument services with OpenTelemetry and use Datadog and CloudWatch to find problems before users do. You prof