Backend Engineer – Python / FastAPI / LLM Pipelines | 100% Remote

We are looking for an experienced Backend Engineer to join an international technology project focused on building an intelligent platform that combines Python backend development, APIs, LLM-based agentic workflows and large-scale data processing .

Location: Spain
Work model: 100% Remote
Environment: International team
️ English: Good professional working proficiency required

What will you be working on?
You will help build and operate the Python backend behind an AI-powered platform used to process, compare, update and evaluate complex technical content.
Your responsibilities will include:
Designing and maintaining REST APIs using Python and FastAPI .
Developing typed API schemas with Pydantic and strong typing practices.
Building asynchronous backend components and secure endpoints.
Developing agentic AI pipelines using LangGraph and LangChain .
Implementing workflows for content discovery, matching, editing, validation and evaluation.
Integrating Azure OpenAI models using structured outputs and function/tool calling.
Developing RAG-based solutions using embeddings and FAISS .
Implementing grounding, provenance and hallucination-control mechanisms.
Processing engineering datasets and large structured XML documents.
Performing data transformations using pandas and openpyxl .
Developing database integrations using SQLAlchemy 2.x, PostgreSQL and AWS Aurora .




Containerizing and deploying backend workloads using Docker and AWS ECS/Fargate .
Working with AWS services such as ECR, Secrets Manager, RDS and SSO .
Maintaining automated testing practices using pytest .

What are we looking for?
Strong professional experience with Python .
Solid experience developing APIs with FastAPI .
Experience with Pydantic, async Python and typed backend development .
Experience with SQLAlchemy and PostgreSQL .
Hands-on experience developing LLM applications using LangGraph and/or LangChain .
Experience integrating OpenAI or Azure OpenAI APIs .
Knowledge of RAG, embeddings, vector search and structured LLM outputs .
Experience implementing techniques to reduce hallucinations and improve LLM output quality.
Experience processing structured or semi-structured datasets.
Knowledge of Docker and AWS cloud services .
Experience with automated testing using pytest .
Experience with XML processing is highly valued.
Experience with AWS Aurora, ECS/Fargate or RDS Data API is a plus.
Good professional English communication skills.

Technology Stack
Python · FastAPI · LangGraph · LangChain · Azure OpenAI · RAG · FAISS · Pydantic · SQLAlchemy · PostgreSQL · AWS Aurora · Docker · ECS/Fargate · pandas · XML · pytest

If you enjoy working at the intersection of backend engineering, generative AI and cloud-based data processing , we would love to hear from you.

📌 Backend Engineer – Python / FastAPI / LLM Pipelines | 100% Remote (Madrid)
🏢 Infoser New Technologies
📍 Madrid