AI Software Engineer

As an AI Software Engineer in our AI Product Team, you will be responsible for the technical design, development, and delivery of AI-driven features and integrations within our platform. You will work with our engineering and delivery teams, product managers and prompt engineers to deliver innovative and effective AI solutions that meet our customers’ needs and expectations. This role will require strong technical skills and knowledge of the software life cycle, an excitement and curiosity for the potential of AI alongside effective communication skills. You will be expected to work primarily within the existing ZellisONE technical architecture stack and will be expected to upskill quickly with this technology but may also be required to build tools in Python and use emerging technologies such as MCP.

Qualifications

AI Application Development:

• Design, build, and maintain AI-powered applications and integrations within our ZellisONE technology stack and ecosystem, ensuring scalability, maintainability, and performance in collaboration with various teams.

AI Engineering Approach:

• Offer expertise and input into our evolving AI approach and pipeline – including prompt engineering, RAG and semantic data retrieval techniques, CoT (Chain or Thought), ensemble models, fine tuning models, RLHF, Agentic workflow and MCP.

Full Stack Engineering:

• Develop efficient and reusable software components using JavaScript, Python, and Javascript frameworks such as Vue and Node, ensuring a seamless user experience. You will be expected to work primarily with the existing ZellisONE technology stack.

Code Quality & Usability:

• Maintain high standards of code quality through structured code reviews, adherence to best practices, and collaborative development via GitHub.

• Ensure usability principles are embedded in all feature implementations, focusing on intuitive design and end-user experience.

AI Testing & Toolset:

• Understand latest tools and trends in AI testing – including performance, consistency and responsibility
• Ensure clear documentation of testing processes and outcomes, maintaining a strong focus on reliability and reproducibility.

Continuous Integration & Delivery:

• Contribute to CI/CD pipelines using modern DevOps tools, ensuring efficient deployment processes and system stability.

Time & Project Management:

• Manage tasks effectively to meet deadlines and delivery milestones.
• Collaborate closely with product managers, designers, and AI specialists to ensure alignment with business objectives.

Innovation & Research:

• Stay informed of emerging trends in AI, machine learning, and software development, and proactively suggest enhancements or new approaches.

Reporting:

• Provide regular updates, insights, and technical documentation to the Head of AI Development and HCM, ensuring transparent communication on project status, risks, and outcomes.

To be successful in this role you will be able to demonstrate:

• Strong proficiency in JavaScript (ES6+) and Python.
• Solid understanding of SQL.
• Working knowledge of GitHub for version control and collaboration.
• Familiarity with AI and code-assist tools such as Codex and Cursor.
• Experience implementing automated and unit testing frameworks.
• Excellent understanding of software usability principles.
• Effective time management and ability to deliver high-quality output to tight deadlines.
• Strong communication, analytical, and problem-solving skills.
• Proven ability to work collaboratively in an agile, product-focused environment.

Benefits

At Zellis we create market-leading HR & Payroll products and services, to power exceptional employee experiences so that you and your people do better. Our multi-award-winning products pay over five million employees a year, with almost half (42%) of the FTSE 100, 50% of the top retailers and 30% of the top universities in the UK & Ireland as customers, making us the largest provider of Payroll and HR software and managed services.

Our vision is to be the clear leader in pay, reward, analytics, and people experiences. We're passionate about creating an environment where people want to join, belong to, and be part of a progressive organisation. Our values, which were defined with input from all of our 2,000 colleagues, we live and breathe every day:

• Unstoppable together.
• Always learning.
• Make it count.
• Think scale.

Our people are critical to our ongoing success; we’re proud of our inclusive culture that gives you the platform to grow, challenge the status quo and play a crucial role in further enhancing our market position as the leading provider of HR & Payroll software and services. With Zellis you’ll have the chance to stretch and challenge yourself in an environment that’s varied, flexible and hugely supportive.

We also love to reward and recognise our brilliant colleagues. As part of your benefits package, you’ll receive:

• A competitive base salary.
• 25 days annual leave, plus your birthday off and the opportunity to buy additional holiday.
• Private medical insurance.
• Life assurance 4x salary.
• Enhanced pension scheme with company contributions up to 8.5%.
• A huge range of additional flexible benefits across financial & personal wellbeing, lifestyle & leisure.