Product Engineer (Up to £150k + 1% Equity) at Calibre

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Job Title

Product Engineer

Salary

Up to £150k + 1% Equity

Company Description

Calibre is a $3.3M seed-funded AI-native certification body founded by ex-Palantir technical leaders and AI researchers. Backed by top-tier San Francisco VCs, the company develops core technologies to independently assess AI and cybersecurity risks, building the essential trust layer for the rapidly evolving autonomous AI economy.

Job Description

Join Calibre's founding team to build a new class of products supercharging AI-native certification. You will own the full stack, engineering reliable agent systems with sophisticated evals and safeguards. This role demands language-agnostic development and deep LLM integration, driving the frontier of AI security and trust from discovery to production.

Location

London, UK

Why this role is remarkable

• Join a founding team of ex-Palantir technical experts and AI researchers backed by $3.3M from premier San Francisco venture capital firms.
• Solve the critical trust gap in AI by building the infrastructure required to certify increasingly autonomous and complex systems for enterprise use.
• Enjoy significant ownership and high autonomy, with up to 1% equity, while working on frontier problems in AI infrastructure and security.
  
  

What You Will Do

• Own and ship high-velocity code across the entire stack, including front-end, back-end, and sophisticated AI-agent infrastructure.
• Design and engineer reliable agent systems, implementing harnesses, evals, and safeguards to ensure non-negotiable quality and hallucination containment.
• Manage products through their entire lifecycle, from initial discovery and first-principles system design to final production deployment and monitoring.
  
  

The ideal candidate

• Demonstrates deep AI engineering expertise, specifically building agent harnesses, tool design, sandboxing, and performance optimization for LLM-based systems.
• Possesses 2+ years of experience in high-growth startups, holds a top-tier CS degree, or has solved complex AI infrastructure and compliance problems.
• Operates as a language-agnostic product engineer who uses LLMs as a force multiplier and prioritizes impactful user outcomes over technical vanity.
  
  

Who are Jack & Jill?

Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.

And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate.

How does this work?

• Jack's an AI agent for job searching and career coaching. He works for you.
• Jill is the AI recruiter working for the company. She recruits from Jack's network.
• If it's a match and the company wants to meet you, they'll make the intro. In the meantime, if you'd like, Jack will send you excellent alternatives.
  
  

We never post fake jobs

This isn't a trick. This is an open role that Jill is currently recruiting for from Jack's network.

Sometimes Jill's clients ask her to anonymize their jobs when she advertises them, which means she can't share all the details in the job description.

We appreciate this can make them look a bit suspect, but there isn't much we can do about it.

Give Jack a spin! You could land this role. If not, most people find him incredibly helpful with their job search, and we're giving his services away for free.