About the Role:

We are looking for a hands-on Senior Python Backend Engineer to build and scale an AI-driven sustainability platform. The role combines Python backend engineering, API development, data processing, and applied AI/LLM workflows.

You will work closely with engineering, product, QA, and domain experts to convert complex requirements into reliable, scalable, and production-ready solutions.

Key Responsibilities:

- Design, develop, and maintain scalable FastAPI/Python backend services and REST APIs.

- Build LLM/RAG-based applications, including prompt workflows, structured outputs, retrieval, grounding, and guardrails.

- Develop rule-based validations and workflows with proper traceability and auditability.

- Build reliable Celery-based background jobs with retries, monitoring, and failure recovery.

- Design data models and optimise PostgreSQL/SQL queries, caching, latency, and application performance.

- Write unit and integration tests using pytest and maintain high engineering standards.

- Contribute to Docker, Git, CI/CD, observability, security, and cloud deployments.

- Troubleshoot issues across applications, databases, distributed jobs, and third-party integrations.

- Collaborate with product, QA, engineering, and sustainability/LCA specialists to deliver features in Agile sprints.

Required Skills:

- 5+ years of professional software development experience with strong hands-on Python backend expertise.

- Strong production experience with FastAPI, Python, Pydantic, asynchronous programming, and service architecture.

- Good knowledge of REST APIs, authentication, validation, error handling, and API versioning.

- Strong experience with PostgreSQL/relational databases and SQLAlchemy or similar ORM.

- Hands-on experience with Celery and Redis/RabbitMQ or similar messaging systems.

- Experience developing LLM applications, RAG, embeddings, semantic search, structured outputs, or vector databases.

- Experience with pytest, Docker, Git, code reviews, CI/CD, and cloud-based applications.

- Strong debugging, analytical, and problem-solving skills.

- Good communication and ability to work with both technical and non-technical stakeholders.

- Interest in sustainability, climate technology, ESG, LCA, or carbon accounting is preferred.

Good to Have:

- Experience with LangChain, LlamaIndex, or similar LLM frameworks.

- Knowledge of LLM evaluation, hallucination control, retrieval quality, and human-in-the-loop workflows.

- Experience with vector databases, search/ranking systems, Pandas, NumPy, or data-processing workloads.

- Exposure to Sentry/monitoring, structured logging, microservices, Kubernetes, or infrastructure-as-code.