(Senior) Machine Learning Engineer

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 more than 2× year‑over‑year.

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.

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

About the Role

(Senior) Machine Learning Engineers at Cleo work on building novel solutions to real‑world problems. This can include creating chatbots to coach users around their financial health, building classifiers to better understand transaction data, or optimising transactions within our payments platform.

Ultimately, we’re looking for a brilliant (Senior) Machine Learning Engineer to join us on our mission to fight for the world’s financial health. You’ll lead technical work within a team of adaptable, creative, and product‑focused engineers, training and integrating cutting‑edge machine learning across a variety of products and deploying them into production for millions of users.

What You’ll Be Doing

• Training and fine‑tuning models to solve customer problems.
• Deploying these models into our production environments using our in‑house ML platform, or integrating with LLMs hosted by OpenAI, Anthropic, GCP, AWS, and others.
• Working cross‑functionally with backend engineers, data analysts, UX writers, product managers, annotation teams, and others to ship features that improve our users’ financial health.
• Taking the initiative to propose and lead technical work toward problems that were previously unknown or poorly understood, driving change at the chapter level that affects multiple squads.
• Mentoring and advising colleagues on model choices, architecture, and evaluation, promoting best practices for how we use LLMs.

Examples of Product Feature Work

• Developed deeper understanding of users’ finances through models extracting meaning from transactional data.
• Developed contextual intent classifiers to understand what conversations users are having with Cleo, enabling controlled responses.
• Built ML models to understand the actions that users have available to them in Cleo and provide those contextually in conversations.
• Built ML models to assess the risk of customers using bank transaction features and user activity.
• Built models to optimise payment success for our customers while optimising costs for the business—a two‑sided optimisation problem.

What You’ll Need

• Excellent knowledge of both Data Science (Python, SQL) and production tools.
• Deep understanding of probability and statistics fundamentals.
• Big‑picture thinking to correctly diagnose problems and productionise research.
• Top‑tier communication skills, to partner with Product and Commercial Leaders.
• Industry‑leading contributions to your field, communicated through conferences, blogs, talks, or open‑source projects.
• Advanced degree in a quantitative discipline or equivalent commercial experience.

Nice to Have

• Strong experience with additional programming languages, such as Java, Scala, C++.
• Industry‑leading contributions to your field, communicated through conferences, blogs, talks, or open‑source projects.

Recruitment Process

• Interview with a Recruiter (30 minutes)
• Interview with the Hiring Manager (30 minutes)
• Python Coding Interview (45 minutes)
• White‑boarding session (60 minutes)
• Technical Discussion (45 minutes)

What Do You Get for All Your Hard Work?

• A competitive compensation package (base + equity).
• Mid‑level (L2):
  • London, UK Hybrid: £75,000 – £95,000 gross annually
  • UK Remote: £69,000 – £87,000 gross annually
• Senior‑level (L3):
  • London, UK Hybrid: £95,000 – £120,000 gross annually
  • UK Remote: £87,000 – £110,000 gross annually
• Work at one of the fastest‑growing tech start‑ups, backed by top VC firms, Balderton & EQT Ventures.
• A clear progression plan with support for growth, leadership, and ownership of impact.
• Flexibility and a healthy work environment—global distribution, hybrid options, travel coverage.
• Company‑wide performance reviews every 4 months with generous pay increases for high performers.
• Equity top‑ups awarded across all levels in performance reviews.
• 25 days annual leave + public holidays (+ an additional day per year at Cleo, up to 30 days).
• 1 month paid sabbatical after 4 years at Cleo.
• Employer‑matched pension (6%) in the UK.
• Private medical insurance via Vitality, dental cover, and life assurance.
• Online mental health support via Spill.
• Enhanced parental leave and workplace nursery scheme.
• Paid access to multiple AI platforms (ChatGPT, Codex, Claude) and the latest AI coding models.
• Choice of Windows or Apple computer.
• Regular socials and activities, online and in‑person.
• And many more!

Final compensation will be determined based on seniority, qualifications, skills, and previous experience.

EEO Statement

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.

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