Senior AI Engineer Job at Xelix (London)

Senior AI Engineer

Xelix

Location:
United Kingdom , London

Category:
IT - Software Development

Contract Type:
Not provided

Salary:

80000.00 - 90000.00 GBP / Year

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Job Description:

At Xelix, we work with some of the world’s largest companies to automate and strengthen their financial controls. Our AI solutions redefine how Accounts Payable teams operate – moving from manual processes to automated, intelligent workflows. Xelix is a fast-paced scale-up – things move fast and expectations are high. We raised our Series B with Insight Partners in June 2025 and are expanding aggressively. We have a team 150 talented people pulling together to achieve our goals. Everyone is trusted to take ownership, move fast and have a meaningful impact. We prioritise personal and professional growth, keep things fun, and love to celebrate a milestone together. In this role you’ll grow, be challenged and help shape the future of Xelix. If you’re excited about building something special with us, we’d love to hear from you. We are hiring a Senior AI Engineer to help shape our AI systems and technical direction. You’ll lead the design and delivery of complex, production-grade AI solutions — combining machine learning, LLMs, and robust engineering practices to build high-impact products. We are a team of builders, focused on systems that work reliably in production, not just prototypes. We use modern AI tools extensively, enabling engineers to operate at a higher level — focusing on architecture, system design, and delivering meaningful product impact.

Job Responsibility:

System Design & Ownership: design and lead end-to-end AI systems, from problem framing through to production deployment and iteration
Advanced AI Systems & Agents: architect complex agent-based workflows, tool ecosystems, and multi-step reasoning systems
Model Strategy: make decisions on model selection, fine-tuning, and when to use ML vs LLM vs hybrid approaches
Evaluation & Quality: define evaluation frameworks, metrics, and feedback loops to ensure reliability and continuous improvement
Production Excellence: ensure systems are scalable, observable, and robust in real-world environments
Technical Leadership: mentor other engineers, review designs, and raise the bar for engineering and AI practices across the team
AI-Assisted Engineering: drive effective use of AI tooling within the team, improving productivity without compromising quality
Cross-Functional Impact: work closely with product and leadership to shape what we build and why

Requirements:

5+ years building and deploying ML or AI systems, with significant experience in production environments
Strong System Design Skills: ability to design end-to-end AI systems and make sound architectural decisions
Deep AI Expertise: strong experience with LLM systems (agents, tool use, evals) and/or traditional ML where appropriate
Pragmatism: ability to choose the right approach for the problem, balancing complexity, performance, and cost
Evaluation Mindset: experience designing and using evals to drive system improvements
Engineering Excellence: high standards for code quality, testing, and maintainability
Leadership & Mentorship: experience guiding other engineers and influencing technical direction
AI-Native Workflow: strong ability to leverage AI-assisted development tools effectively and thoughtfully

What we offer:

27 days of annual leave (including 3 days Christmas closing) which increases up to 3 days based on tenure, with the option to roll over, buy or sell up to 3 days
Hybrid working with two days a week from our dog-friendly Hoxton office
On-site gym and cycle to work scheme
Employee discount at over 100 retailers
Comprehensive private medical & dental cover with Vitality
Enhanced parental leave pay
Learning & development culture – £1,000 personal annual budget
We’re carbon-neutral and are working towards ambitious carbon reduction goals
Lots of team socials & activities
Annual team retreat

Additional Information:

Job Posted:
April 05, 2026

Employment Type:

Fulltime

Work Type:

Hybrid work

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