Senior AI Engineer

Hack The Box; London; Hybrid; GBP 75,000 - 95,000; Full time

Job summary

A leading cybersecurity training company is looking for a Senior AI Engineer to lead the development of agent-powered applications. You will work closely with a team to implement features using Python and Elixir and mentor junior engineers. The role offers remote or hybrid work arrangements and emphasizes a supportive work culture with opportunities for continuous learning and fun.

Benefits

Paid paternity leave

25 annual leave days

Free lunch & snacks

Budget for training and development

State-of-the-art equipment

Qualifications

• Hands-on experience with agentic frameworks.
• Proficiency in building secure REST or GRPC services.
• Solid SQL experience with compliance focus.
• Experience guiding feature squads and coding standards.

Responsibilities

• Lead delivery of agent-powered applications.
• Collaborate with product, design, and researchers.
• Mentor engineers and shape technical roadmap.

Skills

LangChain / LangGraph

Python (FastAPI)

Elixir

PostgreSQL

AI/ML deployment

Erlang

Excellent communication

Job description

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Welcome! Super excited you dropped by
Let's redefine cyber security expertise standards and connect business - community through highly engaging hacking experiences. (Find out more insights about Hack The Box culture in our career site).

The core mission of the Senior AI Engineer:

Join our fast-growing team at the intersection of cybersecurity and AI, where you'll lead the end-to-end delivery of agent-powered applications that protect enterprises at scale. As a Senior AI Engineer, you'll own feature development across Python/Elixir APIs and modern agent-frameworks (LangChain, Argo, CrewAI, SmolAgents).

Our culture prizes autonomy, technical craft, and the drive to ship secure software that outsmarts attackers.

Location & Work Mode:

Options: Preferably UK or Greece but open for Europe

Fully Remote / Hybrid (2 days in the office, 3 days remote, plus one month of work from anywhere) - If only in Greece: When hiring in Greece, we’re open to candidates from all locations. Those based within 55 km of our Athens office will follow a hybrid work model. For candidates located beyond that radius, a fully remote arrangement is available.

The fellowship you’ll be joining:

Reporting to the VP of Artificial Intelligence, you will be part of a 7 people team. You'll collaborate with product, design, and security researchers to turn complex detection and response workflows into intuitive, intelligence-driven user experiences—while mentoring engineers and shaping our technical roadmap.

️ Technology tools & weapons you’ll be using:

The adventures that await you after becoming Senior AI Engineer at Hack The Box:

• 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

Skills, knowledge, and experience points required to unlock the role of the Senior AI Engineer at Hack The Box:

• 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
• Experience with Erlang /Elixir is a plus
• 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

What your Hack The Box adventure will have in store:

• You'll have the exhilarating opportunity to contribute to a product that is highly appreciated by users and the cybersecurity community at large
• You'll experience a highly supportive and caring environment, fostering growth, flexibility, and autonomy
• You'll embark on an exciting journey of continuous learning and problem-solving, leveling up as our organization grows
• Most importantly, you'll have a blast at HTB because fun is an essential ingredient in our recipe for success! Just wait until you see our global meet-ups!

The gems you’ll be enjoying as a Senior AI Engineer:

• 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

Our benefits package is designed to provide strong support to our team, but it may vary depending on location and type of employment (, UK, Greece, or engagement through an Employer of Record).

️ The Quest of Becoming Hack The Box’s Senior AI Engineer:

• Level 1: To complete level one’s objective, submit your application.
• Level 2: Meet the Talent Acquisition team. Level’s objective: highlight your past achievements, ambitions, and values.
• Level 3: Meet the hiring team. Level’s objective: connect with the hiring team and share with them your achievements.
• Level 4: Complete 2 assignments that align with day-to-day job-related tasks and responsibilities. Part of the assignment is discussing it with the hiring team in a debriefing session, in order to walk the team through your thinking process.
• Level 5: Congratulations! Not many reach this level . Level’s objective: have a constructive, final conversation with senior leadership to explore the role and your future at HTB.
• Level 6: You've officially received an offer from HTB! To complete the last level and the Quest, all you need to do is accept the offer.
• Quest complete. Congratulations, you’re officially one of us Your next quest: complete the onboarding.
  

Hack Your Career, Today. Join us in this epic adventure of cybersecurity at Hack The Box!

At Hack The Box, we are on a quest to find the most exceptional and enthusiastic talent to join our team. Whether or not you consider yourself a gamer, we value what makes you unique and want to know more about you. This job post provides just a glimpse of the incredible gamified experience our business and consumer customers enjoy through our platforms. So, if you're ready to embark on a journey of growth and adventure, we can't wait to meet you!

ABOUT HACK THE BOX

Hack The Box is the Cyber Performance Center with the mission to provide a human-first platform to create and maintain high-performing cybersecurity individuals and organizations.

Hack The Box is the only platform that unites upskilling, workforce development, and the human focus in the cybersecurity industry, and it’s trusted by organizations worldwide for driving their teams to peak performance. Offering an all-in-one environment for continuous growth, assessment, and recruitment, Hack The Box provides solutions for all cybersecurity domains.

Launched in 2017, Hack The Box brings together the largest global cybersecurity community of more than 3 million platform members. Rapidly growing its international footprint and reach, Hack The Box is headquartered in the UK, with additional offices in the US, Australia, and Greece.

Exciting News:

• Get the most important updates on HTB’slatest year!
• We are super proud to share that HTB’s all three entities across theUK,US, andGreecehave been Certified as a Great Place to Work (Oct 2023-Oct 2024).
• Furthermore, in 2024 the HTB's Greek entity has been listed by the Great Place to Work Institute as the#2 Best Workplacein Greece and#10 Best Workplace in Europe(among Small & Medium Workplaces).
• Take a sneak peek athow it is to be part of HTBand our2023 Global Retreat. Get more insights about our HTB culture and employee experience by visiting the “about us” section of our site, ourcareer site, andGlassdoor.

At Hack The Box, we are committed to fostering a diverse, inclusive, and equitable workplace. We believe that diversity enriches our performance, services, and the communities we serve. As such, we ensure that all job applications are considered solely based on merit, skills, and qualifications. We do not discriminate on grounds of race, color, religion, gender, gender identity or expression, sexual orientation, national origin, genetics, disability, age, or veteran status. We are dedicated to providing a fair and respectful work environment that reflects our values.