Founding AI Engineer

Founding AI Engineer

Full-Time 80000 - 100000 £ / year (est.) No working from home possible
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At a Glance

  • Tasks: Build AI agents that revolutionise revenue teams by managing messy GTM data.
  • Company: Join a well-funded pre-seed startup with a dynamic team of innovators.
  • Benefits: Competitive salary, equity, hardware budget, and generous holiday allowance.
  • Other info: Opportunity to hire and build a team culture around data quality and innovation.
  • Why this job: Be the first engineer and shape the future of AI in a fast-paced environment.
  • Qualifications: 5+ years in backend engineering with a focus on data-heavy systems.

The predicted salary is between 80000 - 100000 £ per year.

We are a pre-seed team, well funded by a top European fund and a strong group of angels and operators. We're building AI agents for GTM — agents that do the work of a revenue team end-to-end: researching accounts, drafting outreach, updating the CRM, triaging inbound, prepping calls, following up. GTM data is the messiest data in the enterprise. It lives across 10+ systems, it's stale, it's permissioned, and full of half-truths people typed into Salesforce on a Friday afternoon. Building agents on top of this without hallucinating and actually getting the job done at scale is the real engineering problem.

About the role: You'd be the first engineer. You set the bar for architecture, evals, and what great looks like. The hard part isn't the agent loop — it's the data and context layer underneath: pulling from Salesforce, HubSpot, Gong, Slack, Notion, Drive and a long tail of broken APIs, then turning that mess into the precise, fresh, permission-aware context an agent needs to take a real action. You'll build both the context layer and the agents on top. Most of your hardest engineering time will be on the data side: ingestion, modelling, freshness, retrieval quality, evals, latency, permissions.

First 90 days: Own the data and context pipeline end-to-end: connectors, ingestion, schema modelling, chunking, embedding, indexing, hybrid search, reranking, serving. Own the agent runtime on top: tool use, planning, multi-step execution, error recovery. Build the eval harness before shipping anything new. Retrieval evals (recall@k, MRR, faithfulness), agent evals (task success, tool-call correctness, hallucination rate), and a CI gate that blocks regressions. We don't ship on vibes. Make the spine decisions: vector store, embedding model, reranker, agent framework (or none), orchestration, observability. By month six you'll have hired the second engineer and shaped the team's culture around data quality, evals, latency, and product taste.

Required: 5+ years of production backend experience, with meaningful time on data-heavy systems — retrieval, search, recsys, streaming pipelines, or ML infra with real users and real SLAs. You think data first. Schema design, freshness SLAs, idempotency, dead-letter handling, schema drift, CDC — second nature. Bad data in, bad agents out, and you've felt that pain. Shipped a non-trivial RAG, semantic search, or agent system end to end. You can talk fluently about why you chunked the way you did, how you measured it, and what broke. Strong opinions on hybrid retrieval. You know when BM25 beats embeddings, when SQL beats both, and you've made those calls in production. Eval-obsessed. You've built (not just used) eval pipelines for retrieval and agent behaviour. Comfortable owning infra without a platform team. Latency-budget thinking is second nature.

(nice to have) Python or Go fluency. Strong signal: Agents in production, not just RAG. You know what tool-use looks like with 40 tools, and how to keep an agent from looping forever. Multi-tenant systems with row- or document-level access control. You know what happens when permissions desync from the index. Messy GTM stack integrations — Salesforce, HubSpot, Gong, Outreach, Apollo — and the scars to show for it. Data governance or security overlap: lineage, audit trails, PII handling, prompt injection defence.

Interview Process: Four stages, no filler. Founders call (60 min, remote). What you've built, what you'd own here, whether we'd want to spend years in the trenches together. Technical deep-dive 1 (90 min). Walk us through a data-heavy system you've built. Technical deep-dive 2 (180 min, in-person, London). You and the technical founder build something end-to-end together.

Offer: What we offer top-of-market base for our stage. First-engineer-grade equity. Four-year vest, one-year cliff. Hardware budget you don't have to justify. 25 days holiday + UK bank holidays.

Founding AI Engineer employer: Stealth AI Company

As a pioneering pre-seed team backed by top European investors, we offer an exceptional opportunity for the Founding AI Engineer to shape the future of AI agents in a dynamic and innovative environment. Our culture prioritises data quality and engineering excellence, providing you with the autonomy to build impactful solutions while enjoying competitive compensation, generous equity, and a supportive work-life balance with 25 days of holiday plus UK bank holidays. Join us in London to be at the forefront of transforming messy GTM data into actionable insights, all while fostering your professional growth in a collaborative and forward-thinking team.

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Contact Details:

Stealth AI Company Recruitment Team

StudySmarter Expert Advice🤫

We think this is how you could land Founding AI Engineer

Tip Number 1

Network like a pro! Reach out to people in your industry on LinkedIn or at meetups. We all know that sometimes it’s not just what you know, but who you know that can help you land that dream job.

Tip Number 2

Prepare for those interviews! Research the company and its products inside out. We want to impress them with our knowledge and show that we’re genuinely interested in what they do.

Tip Number 3

Practice makes perfect! Do mock interviews with friends or use online platforms. We need to be ready to tackle those tricky technical questions and showcase our skills confidently.

Tip Number 4

Apply through our website! It’s the best way to ensure your application gets seen by the right people. Plus, we love seeing familiar faces from our community!

We think you need these skills to ace Founding AI Engineer

Backend Development
Data Ingestion
Schema Design
Data Modelling
Hybrid Search
Retrieval Quality
Evaluation Pipelines

Some tips for your application 🫡

Show Your Passion for Data:When you're writing your application, let us see your enthusiasm for data-heavy systems. Share specific examples of projects where you tackled messy data and how you made it work. We love seeing candidates who think data-first!

Be Clear and Concise:We appreciate clarity! Make sure your application is easy to read and straight to the point. Highlight your relevant experience without fluff, so we can quickly see how you fit into our vision of building AI agents.

Tailor Your Application:Don’t just send a generic application. Tailor it to our job description! Mention your experience with the tools and technologies we use, like Salesforce or HubSpot, and how you've navigated challenges in those areas.

Apply Through Our Website:We encourage you to apply through our website for the best chance of getting noticed. It helps us keep track of applications and ensures you’re considered for the role. Plus, it’s super easy!

How to prepare for a job interview at Stealth AI Company

Know Your Data Inside Out

Since this role is all about handling messy GTM data, make sure you can discuss your experience with data-heavy systems in detail. Be ready to explain how you've tackled schema design, freshness SLAs, and the challenges of bad data affecting agent performance.

Showcase Your Engineering Mindset

Prepare to dive deep into your engineering decisions. Be specific about the systems you've built, the choices you made regarding retrieval methods, and how you measured success. This will demonstrate your eval-obsessed approach and your ability to think critically about data.

Be Ready for Technical Deep-Dives

Expect to engage in technical discussions that require you to walk through a data-heavy system you've built. Practise explaining complex concepts clearly and concisely, as you'll need to collaborate closely with the technical founder during the in-person deep-dive.

Cultural Fit Matters

As the first engineer, you'll shape the team's culture. Be prepared to discuss how you prioritise data quality, evals, and latency. Show enthusiasm for building a strong team dynamic and how you envision contributing to a positive work environment.