Senior Full Stack Developer || UK || Contract - Remote || £400/day || Outside IR35 ||

We are looking for a hands-on Senior Fullstack Developer to build and deliver production-ready features across Next.js/React frontends, Python APIs, event-driven services, and GCP. The role combines frontend engineering, backend development, automation, data integration, and GenAI capabilities, with end-to-end ownership from design and implementation to testing, deployment, and production support.

Key Responsibilities

• Develop scalable frontend applications using React, Next.js, TypeScript, MUI, and TanStack Query.
• Build and maintain Python APIs using FastAPI or similar frameworks, following REST, OpenAPI, and Pydantic standards.
• Design event-driven workflows using Pub/Sub or similar messaging systems, asynchronous workers, retries, and real-time updates through SSE/WebSockets.
• Integrate GenAI/agentic workflows using Google ADK, LangChain, or similar frameworks, including streaming agent responses to the UI.
• Design and manage SQL databases, data models, migrations, and integrations with BigQuery and object storage.
• Deploy and operate services on GCP, including Cloud Run, IAM, secrets management, and secure network configurations.
• Implement automated testing using pytest and Playwright, alongside CI/CD pipelines and infrastructure as code using GitHub Actions and Terraform.
• Establish observability through logging, metrics, tracing, alerting, and frontend monitoring.
• Build data visualisations, dashboards, and 3D visualisation features where required.
• Own features end to end, troubleshoot production issues, establish engineering standards, and collaborate with engineers, scientists, and business stakeholders.

Mandatory Skills

• Strong Python, FastAPI, TypeScript, React, and Next.js.
• REST API design, OpenAPI, Pydantic, and enterprise integrations using SSO/OAuth.
• Event-driven architecture, messaging systems, asynchronous processing, and real-time communication.
• GCP services, secure cloud deployments, SQL databases, and data modelling.
• Automated testing with pytest/Playwright, CI/CD, Terraform, and observability practices.
• Strong problem-solving, communication, and end-to-end delivery ownership.

Good to Have

• BigQuery, data contracts, data governance, and cost-optimised data querying.
• GenAI agents using Google ADK or LangChain.
• MUI, TanStack Query, advanced dashboards, charts, and 3D visualisation.
• Experience with distributed systems, object storage (GCS/S3), and production monitoring.