Senior Software Engineer

Who we are

We are Fluxon, a product development team founded by ex-Googlers and startup founders. We offer full-cycle software development: from ideation and design to build and go-to-market. We partner with visionary companies, ranging from fast-growing startups to tech leaders like Google and Stripe, to turn bold ideas into products with the power to transform the world. 

The role is open to candidates based in Portugal preferably in Lisbon.

About the role

As an AI Engineer at Fluxon, you’ll take the lead in designing, building and deploying AI-powered applications for our clients.

You'll be responsible for:

• System Architecture: Design and implement end-to-end AI systems and their parts, including data ingestion, preprocessing, model inference, and output structuring


• Generative AI Development: Build and optimize RAG (Retrieval-Augmented Generation) systems and Agentic workflows using frameworks like LangChain, LangGraph, ADK (Agent Development Kit), Genkit


• Production Engineering: Deploy models to production environments (AWS/GCP/Azure) using Docker and Kubernetes, ensuring high availability and scalability


• Evaluation & Monitoring: Implement feedback loops to evaluate model performance (accuracy, hallucinations, relevance) and set up monitoring for drift in production


• Collaboration: Work closely with other engineers to integrate AI endpoints into the core product and with product managers to define AI capabilities


• Model Optimization: Fine-tune open-source models (e.g., Llama, Mistral) for specific domain tasks and optimize them for latency and cost

You'll work with technologies including:

Languages

• Python (Preferred)


• Java / C++ / Scala / R / JavaScript   

AI / ML

• LangChain


• LangGraph


• Google ADK


• Genkit


• OpenAI API


• LLM - Large Language Model


• Vertex AI

Cloud & Infrastructure

• Platforms: Google Cloud Platform (GCP) or Amazon Web Services (AWS)


• Storage: Google Cloud Storage (GCS) or AWS S3


• Orchestration: Temporal, Kubernetes

Data Stores

• PostgreSQL


• Firestore


• MongoDB

Monitoring & Observability

• GCP Cloud Monitoring Suite

Qualifications

• 5+ years of industry experience in software engineering roles


• Strong proficiency in Python or any preferred AI programming language such as Scala, Javascript and Java


• Strong understanding of Transformer architectures, embeddings, and vector similarity search


• Experience integrating with LLM provider APIs (OpenAI, Anthropic, Google Vertex AI)


• Hands-on experience with agent workflows like LangChain, LangGraph


• Experience with Vector Databases and traditional SQL / NoSQL databases


• Familiarity with cloud platforms, preferably GCP or AWS


• Understanding of patterns like RAG (Retrieval-Augmented Generation), few-shot prompting, and Fine-Tuning


• Solid understanding of software development practices including version control (Git) and CI/CD

Nice to have:

• Experience with Google Cloud Platform (GCP) services, specifically Vertex AI, Firestore, and Cloud Functions


• Knowledge of prompt engineering techniques (Chain-of-Thought, ReAct, Tree of Thoughts)


• Experience building "Agentic" workflows where AI can execute tools or API calls autonomously

What we offer

• Exposure to high-profile SV startups and enterprise companies


• Competitive salary


• Fully remote work with flexible hours


• Flexible paid time off


• Profit-sharing program


• Healthcare


• Parental leave, including adoption and fostering


• Gym membership and tuition reimbursement


• Hands-on career development