Machine Learning Engineer (Mid/Senior)

TryHackMe · UK & Europe (Remote / Hybrid)

About TryHackMe

TryHackMe is the fastest-growing online cyber security training platform, with a community of more than 9 million learners. We make security skills accessible, hands-on and fun, for individuals and for the businesses that train their teams with us.🥷

About the role

We’re looking for a Machine Learning Engineer to design, build and own production ML systems that shape how millions of people learn cyber security. You’ll work across LLM-powered experiences, recommendation and personalisation, and embedding-based systems that help us understand learners and content.

You’ll work closely with product squads, the data team and engineering. You’ll take problems from a fuzzy idea to a measurable result in production. At senior level, you’ll also set technical direction, raise the bar on ML engineering practice and mentor others.

What you’ll do

• Design, build and run LLM applications in production, including RAG pipelines, agentic workflows and evaluation frameworks, with a focus on quality, latency and cost.

• Evolve Echo, our AI tutor, so it gives learners context-aware, personalised guidance as they work through labs and challenges. (tryhackme.com/echo)

• Build and improve recommendation and personalisation systems, covering next-best-content, learning paths and difficulty adaptation, based on learner behaviour.

• Develop embedding models and pipelines for semantic search, content similarity, skill mapping and learner modelling.

• Own the full ML lifecycle: data pipelines, offline evaluation, A/B testing, deployment, monitoring and iteration.

• Make pragmatic build-vs-buy calls across open-source and hosted models, and decide when to prompt, fine-tune or train.

• Partner with product to define success metrics and tie model improvements to learner outcomes and engagement.

• (Senior) Lead technical design for ML initiatives, mentor engineers and shape our ML platform and standards.

What we’re looking for

• Mid: 3-5 years in ML engineering. Senior: 5+ years, with a track record of leading ML systems end to end.

• Hands-on experience shipping LLM-based products to real users, with practical knowledge of RAG, prompt and context engineering, and LLM evaluation.

• Practical experience building recommendation or personalisation systems at scale.

• Solid understanding of embeddings, including model selection, fine-tuning or adaptation, vector search and retrieval quality.

• Strong Python and software engineering fundamentals: testing, code review, CI/CD and secure coding.

• Experience deploying and operating ML services with Docker, Kubernetes, REST APIs and microservices.

• Comfort with SQL and large-scale data processing.

• Ability to design experiments and reason about metrics, both offline and online.

• Clear communication with both technical and non-technical stakeholders.

Nice to have

• Cyber security background or genuine interest, such as CTFs, homelabs, a security role, or being a TryHackMe user yourself.

• Experience fine-tuning open-source LLMs (LoRA/QLoRA, SFT, preference tuning) and serving them efficiently (vLLM, quantisation).

• Vector databases (pgvector, Qdrant, Weaviate, Pinecone or similar).

• Learner modelling, knowledge tracing or EdTech experience.

• PyTorch, Hugging Face and scikit-learn; MLOps tooling such as MLflow, feature stores and model monitoring.

• Experience with agent frameworks and tool-use or LLM guardrails.

Why TryHackMe?

• High Impact & High Autonomy: Work in a small team where your work directly reaches millions of learners building careers in cyber security, as well as global enterprises, rather than getting lost inside a 500-person engineering department. You’ll have real ownership, a big surface area and a short path from idea to production.

• A Rare Technical Mix: Work across LLMs, recommendation systems and security, all in one role.

• Elite Sports Team Mindset: We foster a candid, direct feedback culture built on rapid execution, high trust and extreme ownership.

• Profitable & Fast-Growing: Enjoy the velocity of an early-stage scale-up backed by the stability of a highly profitable, self-sustaining business.

Benefits & Perks

• 🚣 100% Remote: Work from anywhere within the UK or approved EU regions.

• 💻 Top-Tier Tools: Latest MacBook Pro + budget for any workspace accessories you need.

• 👕 Swag Bundle: Start your journey with exclusive TryHackMe gear.

• 💪 Personal Development: £2,500 annual training budget for certifications, courses, and conferences.

• ⛱️ Company Retreat: Fully paid annual company-wide retreat.

• 🍕 Lunch on Us: Covered during recurring virtual team lunches.

• 🧡 Health Insurance: Provided in regions without universal coverage.

• 🍼 Enhanced Leave: Generous maternity and paternity packages.

• 💸 Pension / 401(k): Company contribution options for retirement savings.

Our Hiring Process

1. Stage 1: Introductory Chat with Talent Partner (~15 mins)

2. Stage 2: Technical & Experience Interview with the Head of Engineering

3. Stage 3: Take-Home AI-Assisted Technical Assessment + Follow up with the Engineers

4. Stage 4: Founders Interview (Culture & Operating Alignment) with Co-Founder