Lead Machine Learning Engineer, Chat Office: United Kingdom Remote: UK

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.

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.
• 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.
• 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
• Work where you work best.We’re a globally distributed team. If you live in London we have a hybrid approach, we’d love you to spend one day a week or more in our beautiful office. If you’re outside of London, we’ll encourage you to spend a couple of days with us a few times per year. And we’ll cover your travel costs, naturally.

Other benefits

• Company-wide performance reviews every 4 months
• Generous pay increases for high-performing team members
• Equity top-ups for team members getting promoted
• 25 days annual leave a year + public holidays (+ an additional day for every year you spend at Cleo, up to 30 days)
• 6% employer-matched pension in the UK
• Private Medical Insurance via Vitality, dental cover, and life assurance
• Enhanced parental leave
• 1 month paid sabbatical after 4 years at Cleo
• Regular socials and activities, online and in-person
• We'll pay for your OpenAI subscription
• Online mental health support via Spill
• Workplace Nursery Scheme
• And many more!

Welcoming Everyone

We strongly encourage applications from people of colour, the LGBTQ+ community, people with disabilities, neurodivergent people, parents, carers, and people from lower socio-economic backgrounds.

If there’s anything we can do to accommodate your specific situation, please let us know.

Download the Test Flight

App access for people in the UK & Europe: If you are an iOS user, please use this link to sign up to our TestFlight version of the app, so you can have a play around with the functionality and features: https://testflight.apple.com/join/fDG9hWng

By submitting this application, I confirm that all the information given by me in this application for employment and any additional documents attached hereto are true to the best of my knowledge and that I have not wilfully suppressed any material fact. I confirm I have disclosed if applicable any previous employment with Cleo AI. I accept that if any of the information given by me in this application is in any way false or incorrect, my application may be rejected, any offer of employment may be withdrawn or my employment with Cleo AI may be terminated summarily or I may be dismissed. By submitting this application, I agree that my personal data will be processed in accordance with Cleo AI's Candidate Privacy Notice

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