AI/ML Engineer

Limbic; Greater London; Hybrid; GBP 90,000 - 140,000; Full time

Benefits offered by this job

Salary + equity share

London office access

25 days PTO

Pension scheme

Enhanced parental leave

Learning budget

Life Days

Mental health support

Job summary

Limbic is building an AI therapist that delivers structured CBT to adults with depression and anxiety, supervised by licensed clinicians. You’ll work at the intersection of computational psychiatry, clinical science, and software engineering to ship end-to-end features that are measured for patient improvement.

The role involves owning problems end to end, framing with clinicians and product managers, shipping changes, and iterating based on measured outcomes.

Qualifications

• PhD in Computational Psychiatry with industry ML/data science experience.
• Or a BSc/MSc in Computational Psychiatry related field plus 2 years ML eng/Data Science experience.
• Proficiency in Python or TypeScript/JavaScript.
• Experience building LLM-powered features and eval-driven development.
• Expert approach balancing product development with scientific rigour.
• Production ML experience or via high-impact publications.
• Experience modeling text data and LLM classifiers; vector-based methods.
• Experience with longitudinal data and databases (SQL/NoSQL).
• Strong understanding of evidence-based mental health care and cognitive behavioral therapy.
• Bias to action: ship in a week; make decisions with partial info.
• Proficiency with Git.
• Ideal but not required: LLM agent harness or real-time voice AI.
• Ability to work from London office on Tue/Thu; remote other days.

Responsibilities

• Improve how the AI therapist runs sessions, including structure, case formulation, and therapeutic techniques, with clinicians.
• Enhance real-time safety systems, risk detection, and agent responses when risk is disclosed.
• Create evaluations and autolabellers aligned with clinician labels to measure care impact.
• Make voice conversations feel natural, responsive, and capable of recovery when conversations go off-script.
• Help patients stay in treatment with AI-assisted reminders and clear expectations; test with experiments.
• Optimize outcome measures like PHQ-9 and GAD-7; refine methods and timing.
• Ship changes safely with incremental rollouts, automated tests, and clinical sign-off for medical device standards.

Skills

Python

TypeScript/JavaScript

LLM features

Eval-driven development

Data science

ML engineering

Git

Education

PhD in Computational Psychiatry

BSc/MSc in Computational Psychiatry related field

Tools

Git

SQL

NoSQL

LLM platforms

Job description

Build the AI therapist that delivers end-to-end CBT to patients in the US: live, clinically supervised, and measured on whether people actually get better.

About Limbic

Limbic’s vision is to ensure the highest quality therapy is accessible to everyone, everywhere.

Limbic has supported more than 820,000 patients across the UK and the US. We are used in over 50% of NHS Talking Therapies services, which makes us the largest-ever deployment of generative AI for direct patient care, and our AI now delivers end-to-end therapy to patients in the US under the supervision of licensed clinicians.

Safety and science come first. We are the only AI mental health chatbot with UKCA Class IIa medical device certification, and the first AI-led mental healthcare company selected for the FDA’s TEMPO pilot. Our results are published in leading scientific journals: in a randomised, double-blind trial published in Nature Medicine, our AI agents scored higher than licensed CBT therapists on a standard measure of therapy skill.

The Role

As an AI/ML Engineer, you will sit at the intersection of computational psychiatry, clinical science, and software engineering. You will join the product team building our AI therapist: a voice agent that delivers structured, evidence-based CBT over the phone to adults with depression and anxiety, with licensed clinicians overseeing every patient’s care.

The product is live and growing week on week, so your work reaches real patients quickly. You will own problems end to end: frame them with clinicians and product managers, ship a change, measure whether it helped, and iterate. Our AI products are built on shared platforms for agents, evaluation and safety, so what you build here is reused across Limbic.

What You’ll Do

• Improve how our AI therapist runs sessions, from session structure and case formulation to therapeutic techniques and continuity across a course of treatment, working closely with clinicians.

• Strengthen the safety systems that protect patients in real time, including risk detection and how the agent responds when risk is disclosed.

• Build evaluations and LLM-as-judge autolabellers, validated against clinician labels, so we know quickly and reliably whether a change made care better or worse.

• Make voice conversations feel natural: responsive, well-paced, and able to recover gracefully when a conversation goes off script.

• Help patients stay with their treatment long enough to recover, through AI features such as well-timed session reminders and clear expectations about what therapy involves, and test what works with experiments.

• Optimise how we collect outcome measures such as PHQ-9 and GAD-7, including the methods, timing and predictive modelling of recovery.

• Ship changes safely through incremental rollouts, automated testing and a clinical sign-off process built for a regulated medical device.

What You’ll Bring

• You must meet one of the following educational and experience backgrounds:

  • A PhD in Computational Psychiatry or a related field, coupled with demonstrated industry experience in Data Science, Product, or ML engineering.

  • OR A BSc/MSc in a Computational Psychiatry related field (research focus) plus 2 years of experience in ML engineering or Data Science within an Engineering/Product Development environment.

• Proficiency in either Python or TypeScript/JavaScript.

• Experience building LLM-powered features and a track record of eval-driven development.

• An expert approach to hypothesis-driven work, with a track record of balancing product development with scientific rigour.

• Experience using Machine Learning in a production environment or via high-impact scientific publications (e.g., predictive modelling, reinforcement learning).

• Experience modelling text/language data, including building LLM classifiers and using vector-based methods.

• Experience modelling longitudinal data and working with databases (SQL or NoSQL).

• A strong understanding of evidence-based mental health care (such as Cognitive Behavioural Therapy) and a deep interest in the causal mechanisms that drive therapeutic benefit.

• A bias to action: you break big problems into pieces you can ship within a week, and you are comfortable making decisions with incomplete information.

• Proficiency with version control systems, preferably Git.

• Ideal but not required: Experience building an LLM agent harness or real-time voice AI.

• The ability to work from our London (Spitalfields) office on Tuesdays and Thursdays, with the flexibility to work remotely or from the office on other days of the week.

Benefits & Wellbeing

• Competitive salary and equity share options.

• An amazing office in central London (Spitalfields) for our collaborative team days on Tuesdays and Thursdays, paired with a flexible/hybrid working model on Mondays, Wednesdays, and Fridays.

• 25 days PTO plus bank holidays.

• Company pension scheme (UK).

• Enhanced parental leave packages (UK).

• Support with purchasing work-related books and materials.

• Quarterly Life Days: Enjoy 4 paid days off per year (one each quarter) to use whenever you choose to relax, recharge, or take care of personal matters.

• Mental Health Support: Access to dedicated mental health support services.

We encourage women and individuals from diverse backgrounds to apply and join our team. We believe in creating an inclusive and supportive work environment where everyone can contribute their best.