Senior AI Engineer

Summary

Join Hack The Box's fast-growing team as a Senior AI Engineer, leading the development of agent-powered applications for enterprise-scale cybersecurity. You will own feature development across Python/Elixir APIs and modern agent frameworks. The role involves collaboration with product, design, and security researchers, turning complex workflows into intuitive user experiences. You'll also mentor engineers and contribute to the technical roadmap. The position offers a flexible work arrangement, with options for fully remote or hybrid work, primarily based in the UK or Greece but open to other European locations. Hack The Box prioritizes autonomy, technical excellence, and secure software development.

Requirements

• Hands-on building with LangChain / LangGraph, Argo, CrewAI, SmolAgents or equivalent libraries to orchestrate multi-step reasoning, tool use, and RAG pipelines
• Proficiency writing, secure REST or GRPC services in Python (FastAPI) or Elixir that integrate LLM inference,vector stores, and streaming data
• Solid SQL and document-store experience (PostgreSQL, Pgvector, BigTable/Cassandra) with attention to least-privilege access and compliance
• AI/ML deployment: Practical knowledge of prompt engineering, evaluation, and model-ops on cloud GPUs or serverless inference platforms
• Experience guiding feature squads, conducting design reviews, and driving coding standards / CI-CD best practices in a senior or tech-lead role
• Excellent written & verbal communication, especially in remote/async environments, with a bias toward documenting architecture and decisions

Responsibilities

• Design and build with modern agentic frameworks like LangChain, Argo, CrewAI, SmolAgents and Google ADK to orchestrate multi-step reasoning, RAG pipelines, and secure tool use
• Implement and maintain REST APIs in Python (FastAPI) or Elixir that integrate LLM inference, vector databases, and streaming security data
• Ensure security and compliance in the data layer by applying least-privilege access controls and working with PostgreSQL with Pgvector, Redis, and other stores
• Mentor engineers and contribute to technical leadership, including code reviews and design sessions
• Document decisions and communicate clearly in a remote-first environment, contributing to a culture of thoughtful async collaboration

Preferred Qualifications

Experience with Erlang /Elixir is a plus

Benefits

• Private health care
• Paid paternity leave
• 25 annual leave days
• Free lunch & snacks at the office
• 120€ Ticket Restaurant by Edenred
• Dedicated budget for training and professional development, participation in conferences
• Full access to the Hack The Box lab offerings; so you can learn how to hack 😉
• State-of-the-art equipment (mac, iPhone, and mobile plan)
• Flexible WFH (Hybrid Model) - Fully Remote is also an option if you're not an Attica resident