Data Scientist

Dependent on experience. Be part of our success with the opportunity to join our company equity scheme.

The Role

Our mission is to help large successful brands like Uber, Amazon, Wise, HelloFresh (and more!) put their customers at the centre of everything they do. Using best-in-class tech in a fast-developing AI space, our Customer Experience Intelligence platform continuously analyses explicit and implicit feedback to enable our clients to identify what they should do next. We're hiring a Data Scientist to join the team and help build and ship the next generation of that stack.

What You'll Be Doing

• Train, evaluate, and iterate on ML models for customer feedback tasks, contributing to our custom fine‑tuning pipelines and running experiments with rigour and clear documentation.
• Build and maintain LLM‑powered features including retrieval pipelines, reranking systems, and insight generation — with support and guidance from senior team members.
• Contribute to evaluation frameworks: help build test sets, define metrics, and assess model quality across classification, extraction, and generative tasks.
• Work on semantic search and retrieval, developing a strong working understanding of embedding‑based approaches and the methods that go beyond them.
• Write clean, well‑tested code and collaborate with Engineering on model integration, data pipelines, and monitoring.
• Work with the wider Data Science team to translate business and product requirements into practical ML experiments and solutions.
• Stay close to relevant research and bring useful ideas from the literature into team discussions and experiments.

What You’ll Need

• A solid working knowledge of transformer architectures and how they are applied in NLP tasks.
• Proficiency in PyTorch, including training loops and standard model fine‑tuning workflows; exposure to parameter‑efficient techniques such as LoRA is a plus.
• Experience working with real‑world text data across tasks such as classification, extraction, embeddings, or search — at a meaningful scale.
• Some exposure to instruction fine‑tuning or model serving, with an interest in going deeper.
• A grounding in classical ML and statistics, and the instinct to reach for simpler methods when warranted.
• Familiarity with GenAI and agentic patterns, even if hands‑on production experience is still developing.
• Clear communication skills and the ability to explain technical work to colleagues across functions.
• Genuine curiosity about AI and a habit of experimenting — you learn by doing.
• Good ownership instincts: you follow problems through rather than passing them on.

Bonus

• MSc in Computer Science, Machine Learning, AI, Data Science, Computational Linguistics, or a closely related STEM field.

Our Hiring Process

• Let’s introduce ourselves – you’ll complete an introductory asynchronous interview - we’d love to learn more about you, your ambitions, and what you’re looking for in your next step.
• Get to know your would‑be manager – you’ll have a call with Aji, our Chief Scientist, to learn more about the role and show off your experience.
• Show us how you work – you'll complete a short take home assignment.
• Get to know your would‑be team – You'll meet a mix of people who you'll be working closely with from the Data Science, Engineering and Product teams.
• How our values and your career goals align – you’ll have a call with our cofounder to learn more about life at Chattermill and ensure we’re the right place for your next stage of growth.

Our Perks

• Flexible working in a choice‑first environment - we trust the way you want to work!
• Work‑from‑home allowance to set up your ideal workspace.
• 25 days holiday + local bank holidays, plus an extra day for each year of service.
• Your birthday off.
• Annual learning & development budget to support your growth (increasing over time).
• Equity options — share in the company’s success.
• Monthly health & wellbeing budget, increasing with length of service.
• Optional private healthcare plan.
• Life assurance & income protection (location dependent).
• Employee Assistance Programme (location dependent) for extra support when you need it.
• Enhanced family leave (location dependent), plus fertility and neonatal leave.

Office Perks

• If you’re in London, a dog‑friendly office with great classes, events, and a rooftop terrace.

Our Values

• We are obsessed with experience – We take our mission to rid the world of bad Customer Experience seriously, and we practice what we preach.
• We believe in the power of trust – Whether it's with each other, our customers, partners, or other stakeholders, we always communicate with openness and trust.
• We act as responsible owners – Whether it's about the company, a team, a project, or a task, having the freedom to make decisions in our area of responsibility is a crucial driver for us.
• We share a passion for growth & progress – On every level, we’re motivated by taking on new challenges – even if they seem out of reach.
• We recognise that we are learning machines and we always seek to action feedback and improve collectively.
• We set our ambitions high but stay humble – We’ve come together to build a product and a category that’s never been seen before. While we’re an ambitious bunch with lofty goals, we don't approach this goal carelessly.
• We believe the right team is the key to success – At Chattermill we’ve learned that all our important achievements have been the result of the right people collaborating together – that’s why we need you to apply today!

Diversity & Inclusion

We want to enable exceptional experiences for everyone, and to achieve this we need everyone’s voice in our team. We are on a mission to bring more diversity into the business and to give everyone (from all backgrounds and abilities) a chance to join us, even if they may not fit all of the requirements set out in this job spec. We realise that some may be hesitant to apply for a role when they don’t meet 100% of the listed requirements – we believe in potential and will happily consider all applications based on the skills and experience you have, we’d love to be part of your growth and we encourage you to apply!