Founding Product Engineer Job in UK 2026 (£130,000 to £150,000)

A fast-growing AI-driven technology startup is hiring a Founding Product Engineer in London for 2026, offering a highly competitive salary of £130,000-£150,000 per year, meaningful equity (1-1.5%), and European Skilled Worker visa sponsorship for eligible international candidates.

This is a rare opportunity for globally minded engineers to join at a founding level, shape core product direction, and build production grade AI systems used daily by elite customers worldwide.

As Founding Product Engineer, you will sit at the intersection of engineering, product, and AI systems design. This is a high ownership role where you will take ambiguous ideas and turn them into real, customer facing features-shipping end to end workflows powered by machine learning and agentic AI.

You'll act as both builder and product owner for key areas of the platform, working directly with founders, domain experts, and engineers to deliver experiences that support time sensitive, high stakes decisions for members. The role is primarily in person from London, with flexible remote days, and offers a clear path toward senior technical or product leadership as the company scales.

• Own user facing product features end to end, from concept through production and iteration
• Act as product owner for assigned areas, balancing user value, technical constraints, and delivery speed
• Design and implement AI powered workflows using LLMs, tools, and agentic systems
• Build ML driven capabilities such as classification, ranking, extraction, and decision support
• Create human in the loop systems combining automation with expert escalation
• Collaborate closely with founders, engineers, and operations teams to ship scalable solutions
• Define success metrics and iterate based on real customer usage and feedback
• Debug production issues related to AI behavior, data quality, and workflow design
• Contribute code across the stack with a strong bias toward shipping impact

• 4+ years of professional experience building production software
• Proven delivery of AI or ML powered features used by real customers
• Hands on experience with LLMs, prompt design, and agent orchestration
• Strong Python skills and solid backend/API fundamentals
• Experience with data pipelines, embeddings, retrieval, or RAG systems
• Product driven mindset with comfort operating in ambiguity
• Ability to reason about latency, cost, reliability, and quality trade offs
• Excellent communication and ownership mentality
• Willingness to work primarily in person with a high performance team

This Founding Product Engineer role offers international candidates a premium entry point into the UK startup ecosystem, combining visa sponsorship, top tier compensation, equity, and deep technical ownership. For engineers seeking to build real world AI systems, influence product strategy, and grow alongside an ambitious founding team in London, this opportunity delivers exceptional career acceleration in 2026.