AI Engineer

Xelix; City of London; Hybrid; GBP 65,000 - 75,000; Full time

Job summary

A growing technology firm in the City of London is seeking a Mid-Level AI Engineer to enhance their AI Engineering team. This role involves developing AI solutions using state-of-the-art technology, including LLMs. Candidates should have 2-5 years of experience with ML features and solid Python skills. The firm offers a competitive salary and hybrid working options, along with benefits that include a gym and generous annual leave.

Benefits

Competitive salary

27 days of annual leave

Hybrid working environment

On-site gym

Employee discounts

Comprehensive private medical cover

Learning & development budget

Annual team retreat

Qualifications

• 2-5 years’ experience delivering ML or LLM-powered features to production.
• Strong Python skills for AI/ML applications.
• Hands-on experience with gradient-boosted models.

Responsibilities

• Design, train, and evaluate end-to-end ML models.
• Build and refine applications leveraging language models.
• Collaborate with teams to deliver high-impact features.

Skills

Python skills for AI/ML applications

Collaboration skills

Hands-on experience with gradient-boosted models

Solid data skills: SQL, pandas

2-5 years’ experience with ML or LLM features

Tools

AWS

Job description

About us

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, whilst remaining profitable. We have over 100 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 & we 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.

About the role

We are now hiring for a Mid‑Level AI Engineer to join our growing AI Engineering team. This role is an exciting opportunity to leverage state‑of‑the‑art technology, including the latest LLMs and AI technologies, to power our tools and develop impactful new solutions for our customers.

What you’ll be doing

• Model Development: design, train, and evaluate end‑to‑end ML models – from preprocessing to deployment – working with text, vision, and tabular data.
• LLM & AI Systems: build and refine applications leveraging large language models, prompt engineering, and agentic frameworks to solve real‑world business problems.
• Production Code: write clean, maintainable Python for AI/ML applications and collaborate with our back‑end team to integrate seamlessly into the platform.
• Experimentation & Research: stay current with the latest AI/ML techniques, test new algorithms and tools, and improve upon existing approaches.
• Collaboration: work closely with product, data, and engineering teams to deliver high‑impact, customer‑facing features.

What you’ll bring

• 2‑5 years’ experience delivering ML or LLM‑powered features to production, from data prep and model training to deployment and iteration.
• Strong Python skills for AI/ML applications – clean, well‑tested code, version control best practice, and smooth integration with back‑end systems.
• Hands‑on experience with gradient‑boosted models (e.g., XGBoost, LightGBM) and/or building LLM‑powered systems (e.g. tool/function calling, prompt design, evals) for text‑heavy tasks.
• Solid data skills: SQL, pandas, experiment tracking, and cloud deployment (AWS a plus).
• A passion for AI/ML, shown through personal projects, a well‑maintained GitHub portfolio, blog posts, or contributions to the AI/ML community.
• Strong collaboration skills – able to work closely with engineers, product managers, and data teams to ship impactful features.

What we offer in return

💰 Competitive salary of £65,000 to £75,000 depending on experience

🏝️ 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

Want to learn more?

• About us
• Xelix blog
• Xelix news
• Xelix glassdoor

We believe that people from diverse backgrounds, with different identities and experiences make our company and product better. No matter your background, we’d love to hear from you! And if you have a disability, please let us know if there’s any way we can make the interview process better for you – we’re happy to accommodate!

If you’re a recruiting agency – we have an existing list of agencies we work with if required and we are not currently planning on expanding the list. Neither the Talent team nor hiring managers or the Support team will respond to cold outreach.

This is a full‑time position, with standard working hours from 9:00 AM to 6:00 PM, Monday through Friday.

Interview Process

While the exact process may vary slightly depending on the role, our typical interview stages are:

1. Introductory Call – A short Teams conversation with a Talent Partner to discuss your background and the opportunity.
2. Hiring Manager Interview – A 30–45 minute Teams meeting to explore your experience and fit for the team.
3. Technical Task or Presentation – A role‑relevant exercise to demonstrate your skills and approach.
4. Final On‑site Interview – An in‑person meeting with our senior leadership team and co‑founders at our office.

We strive to make the process clear, efficient, and respectful of your time.