Founding Product Engineer

Calibre Technologies Inc.; Greater London; Hybrid; GBP 70,000 - 110,000; Full time

Job summary

Calibre Technologies Inc. in London is seeking a Product Engineer to join the founding team and build AI-native certification products, spanning front-end, back-end, and agent infrastructure.

You’ll work from discovery through production, designing systems with a language-agnostic, first-principles approach and a focus on reliable, measurable quality. Collaboration and pragmatic tool choices are valued as outcomes scale.

Qualifications

• Demonstrable AI engineering depth with real systems showing decisions about agent harnesses, evals, hallucination containment, performance, agent sandboxing or MCP/tool design.
• Strong product engineering and technical judgment; ships across interface, backend, data and deployment, reasoned with first principles.
• Product instinct and clear collaboration; asks questions, tests quickly, communicates clearly and cares about outcomes.
• Evidence of shipped work through professional work, open-source contributions, personal projects or hackathon results; ~2+ years useful but evidence matters more.

Responsibilities

• Own products across the whole stack. Build and ship across front-end, back-end and AI-agent infrastructure.
• Build products end-to-end. Design systems from discovery through to production.
• Engineer reliable agent systems. Design harnesses, evals and safeguards that keep quality measurable.

Job description

Engineering London Full-time

We are hiring a Product Engineer to join the founding team and build products for our AI-native certification process. We are hiring a Product Engineer to join the founding team and build products for our AI-native certification process.

You should be language-agnostic, reason from first principles, and use LLMs in your daily engineering workflow. You should be language-agnostic, reason from first principles, and use LLMs in your daily engineering workflow.

• Own products across the whole stack. Build and ship across front-end, back-end and AI-agent infrastructure.


• Build products end-to-end. Design systems from discovery through to production.


• Engineer reliable agent systems. Design harnesses, evals and safeguards that keep quality measurable.

What we're looking for W h a t w e ' r e l o o k i n g f o r

• Demonstrable AI engineering depth. You can show real systems where you made substantive decisions about agent harnesses, evals, hallucination containment, performance, agent sandboxing or MCP/tool design.


• Strong product engineering and technical judgment. You ship across interface, backend, data and deployment, reason from first principles and choose tools deliberately.


• Product instinct and clear collaboration. You ask good questions, form a view, test quickly, communicate clearly and care whether the work changes outcomes.


• Evidence of shipped work. Show us professional work, open-source contributions, personal products, research or hackathon results. Roughly 2+ years of experience is useful, but evidence matters more than tenure.