Senior ML Engineer (LLMS, NLP) in London

Who We Are Is What We Do. Deel is the all‑in‑one payroll and HR platform for global teams. Our vision is to unlock global opportunity for every person, team, and business. Built for the way the world works today, Deel combines HRIS, payroll, compliance, benefits, performance, and equipment management into one seamless platform. With AI‑powered tools and a fully owned payroll infrastructure, Deel supports every worker type in 150+ countries—helping businesses scale smarter, faster, and more compliantly.

Among the largest globally distributed companies in the world, our team of 7,000 spans more than 100 countries, speaks 74 languages, and brings a connected and dynamic culture that drives continuous learning and innovation for our customers.

As the fastest‑growing Software as a Service (SaaS) company in history, Deel is transforming how global talent connects with world‑class companies – breaking down borders that have traditionally limited both hiring and career opportunities. We’re not just building software; we’re creating the infrastructure for the future of work, enabling a more diverse and inclusive global economy. In 2024 alone, we paid $11.2 billion to workers in nearly 100 currencies and provided healthcare and benefits to workers in 109 countries—ensuring people get paid and protected, no matter where they are.

Your experience at Deel will be a career accelerator. At the forefront of the global work revolution, you’ll tackle complex challenges that impact millions of people’s working lives. With our momentum—backed by a $17.3 billion valuation and $1 B in Annual Recurring Revenue (ARR) in just over five years—you’ll drive meaningful impact while building expertise that makes you a sought‑after leader in the transformation of global work.

Get ready to:

• Design and deploy advanced LLM‑powered applications that support our Payroll product lines and operations.
• Lead architecture decisions, cost optimization, and observability efforts for mission‑critical AI workflows.
• Collaborate with ML researchers, product managers, and application engineers.
• Create massive impact by doing groundbreaking work in an already high‑scale product.

You’ll bring:

• 6+ years of engineering experience, ideally in ML systems or large‑scale software, with a strong foundation in system design and architecture.
• Hands‑on experience implementing research and algorithms in Python, focused on information retrieval, text processing, NLP, LLMs, and machine learning.
• Experience building production‑grade LLM applications, including fine‑tuning or adapting base models for domain‑specific tasks.
• Deep understanding of vector databases (e.g. Pinecone, Weaviate, FAISS) and how they fit into retrieval‑augmented generation and context retrieval pipelines.
• Python expertise for AI/ML development and Node.js familiarity for integration with product and application teams.
• Knowledge of prompt engineering, LLM API integration, and system reliability patterns for scaling AI in production.
• Experience with observability and cost optimization across AI infrastructure (tracing, metrics, performance tuning).

Bonus:

• Cost tracking and model optimization for AI workloads.
• RAG implementations, LangChain/CrewAI experience.
• Background in classical ML or pre‑LLM NLP.
• Exposure to multimodal systems.

Total Rewards: Our workforce deserves fair and competitive pay that meets them where they are. With scalable benefits, rewards, and perks, our total rewards programs reflect our commitment to inclusivity and access for all.

Some things you’ll enjoy:

• Stock grant opportunities dependent on your role, employment status, and location.
• Additional perks and benefits based on your employment status and country.
• The flexibility of remote work, including optional WeWork access.

At Deel, we’re an equal‑opportunity employer that values diversity and positively encourage applications from suitably qualified and eligible candidates regardless of race, religion, sex, national origin, gender, sexual orientation, age, marital status, veteran status, disability status, pregnancy or maternity or other applicable legally protected characteristics.

Unless otherwise agreed, we will communicate with job applicants using Deel‑specific emails, which include @deel.com and other acquired company emails like @payspace.com and @paygroup.com. You can view the most up‑to‑date job listings at Deel by visiting our careers page.

Deel will provide accommodations on request throughout the recruitment, selection and assessment process for applicants with disabilities. If you require accommodations, please inform our Talent Acquisition Team via this link and a team member will be in touch to ensure your equal participation.

If you have difficulty accessing the form, please email at. As part of our hiring process, we primarily rely on interviews and role‑related assessments. In limited cases, we may also consider informal background information relevant to the role, in line with our privacy and fairness obligations.

This application process may utilise Automated Employment Decision Tools (AEDT) and AI systems to assist in evaluating candidates based on experience level, technical skills and qualifications. This processing is conducted in compliance with applicable Data Protection, AI Governance and Labour Laws. We ensure human oversight is maintained in all final hiring decisions. Your personal data is not used to train AI models. For more information on how we process your personal data, please see our Privacy Policy.

For NYC Residents: In accordance with NYC Local Law 144, an independent bias audit has been conducted on AEDT; results are available at Ashby, Covey.