Senior AI Engineer

83zero Limited; Cardiff; On-site; GBP 74,000 - 129,000; Full time

Job summary

83zero Limited is seeking a Senior AI Engineer for a hands-on contract role in Cardiff, with some onboarding time in Cardiff and occasional travel. Inside IR35, £400-£700 per day, you will lead production AI/ML work and shape technical strategy.

You'll write production code, guide engineering teams, evaluate build-versus-buy options, and deploy AI workloads on AWS (Bedrock or SageMaker) while ensuring security, privacy and data residency requirements.

Qualifications

• Strong hands-on experience building production AI/ML systems.
• Excellent software engineering and production coding skills.
• Proven experience deploying AI/ML workloads on AWS.
• Knowledge of Bedrock or SageMaker, alongside services such as S3, IAM and Lambda.
• Practical experience designing and implementing RAG systems.
• Experience with prompt engineering, structured outputs, function calling and tool use.
• Strong understanding of AI evaluation, testing and production monitoring.
• Experience handling security, privacy, tenant isolation and data-residency requirements.
• Ability to explain technical trade-offs, build consensus and lead through influence.

Responsibilities

• Lead and deliver AI-powered features from prototype through to production.
• Write significant production code while guiding other engineers.
• Set the technical direction for AI and machine learning.
• Design and deploy AI/ML workloads using AWS, particularly Bedrock or SageMaker.
• Make and justify architectural and build-versus-buy decisions.
• Evaluate commercial APIs, hosted platforms and self-hosted or open-weight models.
• Balance capability, cost, latency, scalability and data-control requirements.
• Work closely with established product and engineering teams.

Skills

Production AI/ML

AWS deployment

Architectural decisions

Technical leadership

Prompt engineering

RAG systems

Security & privacy

Model evaluation

Tools

Bedrock

SageMaker

S3

IAM

Lambda

Open-weight models

Job description

Senior AI Engineer - Contract

Inside IR35 - £400-£700 per day

The role

We’re looking for a senior, hands-on AI Engineer who can both build and lead.

This contract role sits at the centre of an ambitious AI strategy. You’ll write production code while guiding existing engineering teams towards the right solutions-making sound architectural decisions, assessing build-versus-buy options and avoiding technical dead ends.

This is technical leadership rather than people management. You’ll be equally comfortable shaping an approach with the team and implementing it in the codebase. You’ll take product goals, assess the viable options, recommend a defensible approach and help deliver it within a regulated production environment.

Core responsibilities

• Lead and deliver AI-powered features from prototype through to production.
• Write significant production code while guiding other engineers.
• Set the technical direction for AI and machine learning.
• Design and deploy AI/ML workloads using AWS, particularly Bedrock or SageMaker.
• Make and justify architectural and build-versus-buy decisions.
• Evaluate commercial APIs, hosted platforms and self-hosted or open-weight models.
• Balance capability, cost, latency, scalability and data-control requirements.
• Work closely with established product and engineering teams.

Experience required

• Strong hands‑on experience building production AI/ML systems.
• Excellent software engineering and production coding skills.
• Proven experience deploying AI/ML workloads on AWS.
• Knowledge of Amazon Bedrock or SageMaker, alongside services such as S3, IAM and Lambda.
• Practical experience designing and implementing RAG systems.
• Experience with prompt engineering, structured outputs, function calling and tool use.
• Strong understanding of AI evaluation, testing and production monitoring.
• Experience handling security, privacy, tenant isolation and data-residency requirements.
• Ability to explain technical trade-offs, build consensus and lead through influence.

Additional experience valued

• Topic modelling, document classification, clustering and entity extraction.
• Document-ingestion and extraction pipelines covering PDFs, Office documents, images and tables.
• Multimodal processing and embedding generation.
• Agentic workflows in which LLMs plan, call tools and complete multistep tasks.
• Optimising LLM workloads for cost, latency and throughput.
• Experience within financial services, fintech or another regulated environment.

This opportunity would suit a senior AI Engineer or Technical Lead who remains genuinely hands‑on and can combine production delivery with pragmatic technical leadership.

Location

The role will require some time in Cardiff during the onboarding period, followed by occasional travel to Cardiff throughout the contract.