Lead Machine Learning Engineer, Chat

About The Company

About Cleo

At Cleo, we're not just building another fintech app. We're embarking on a mission to fundamentally change humanity's relationship with money. Imagine a world where everyone, regardless of background or income, has access to a hyper-intelligent financial advisor in their pocket. That's the future we're creating.

Cleo is a rare success story: a profitable, fast-growing unicorn with over $300 million in ARR and growing over 2x year-over-year. This isn't just a job; it's a chance to join a team of brilliant, driven individuals who are passionate about making a real difference. We have an exceptionally high bar for talent, seeking individuals who are not only at the top of their field but also embody our culture of collaboration and positive impact.

If you’re driven by complex challenges that push your expertise, the chance to shape something truly transformative, and the potential to share in Cleo’s success as we scale, while growing alongside a company that’s scaling fast, this might be your perfect fit.

Follow us on LinkedIn to keep up to date with new product features and insights from the team.

About The Role

Machine Learning Engineers at Cleo work on building novel solutions to real-world problems. This really does vary but could be: creating chatbots to coach our users around their financial health, creating classifiers to better understand transaction data or even optimising transactions within our payments platform. They train, deploy, and improve machine learning models in production, ensuring they deliver meaningful impact for our users.

We’re looking for our next Lead Machine Learning Engineer to join our

Chat Evaluations

team. You’ll shape & guide technical work within a team of adaptable, creative and product-focused engineers, who deliver ML/AI features that improve the observability of chatbot quality and power the AI development cycle.

Here Are Some Examples, Big And Small, Of The Kinds Of Product Feature Work Our ML Engineers Have Taken Part In Over The Last Year

• Deployed best-in-class credit decisioning models which affect millions of customers, using open banking data rather than traditional credit scoring

• Developed models to interpret transactional data, enhancing the understanding of users’ finances. Think about your bank statement—how often do you not recognise a transaction on first review?

• Fed user interaction data into fine-tuned LLMs and contextual ranking models, so Cleo knows how to start and continue an engaging conversation.

• Developed optimisation models to improve payment success rates for customers while minimising business costs, tackling this as a two-sided optimisation challenge.

• Designed and implemented AI agents to analyse and extract insights from users’ transactional data.

Check out this blog on Isabelle's journey in ML at Cleo.

What we're looking for

Must have

• Experience deploying multiple machine learning models into production

• 5+ years of experience in data science, machine learning engineering, or related roles

• Experience integrating and evaluating LLMs

• Excellent knowledge of both Data Science (Python, SQL) and production tools

• Understanding of probability and statistics fundamentals

• Strong ability to communicate findings to non-technical stakeholders

• Experience of leading projects involving multiple people including developing a short term roadmap and reporting progress

• Comfortable breaking down work incrementally

Nice to have

• Familiarity with Docker containers and container orchestration tools

• Experience with LLM-as-a-judge and/or annotation pipelines

The recruitment process

• Talent Screen with a Talent Partner (30 mins)

• Interview with the Hiring Manager (30 mins)

• Python coding Interview (45 mins)

• White-boarding session (60 mins)

• Technical Discussion (45 mins)

What do you get for all your hard work?

• A competitive compensation package (base + equity) with 3-yearly reviews, aligned to our termly OKR planning cycles.

• The salary bandings for this role are: £116,510 - £144,319 London, Hybrid / £111,296 - £139,273 UK, Remote

• Work at one of the fastest-growing tech startups, backed by top VC firms, Balderton & EQT Ventures

• A clear progression plan. We want you to keep growing. That means trying new things, leading others, challenging the status quo and owning your impact. Always with our complete support.

• Flexibility. We can’t fight for the world’s financial health if we’re not healthy ourselves. We work with everyone to make sure they have the balance they need to do their best work

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