Founding Engineer AI

W Talent; City Of London; Hybrid; GBP 80,000 - 100,000; Full time

Job summary

A fast-growing AI startup in London is seeking a Founding Engineer to lead the design and development of production AI systems. You'll have real ownership, shaping architecture and tooling, while ensuring systems are safe and reliable. Ideal candidates will have 4+ years of backend engineering experience and knowledge of building LLM applications. This role offers a competitive salary and the opportunity to work in a hybrid environment.

Qualifications

• 4+ years of backend engineering experience, preferably in TypeScript, Python, or Kotlin.
• Hands-on experience shipping LLM applications or AI agents.
• Solid understanding of prompt engineering and evaluation techniques.

Responsibilities

• Architect scalable LLM-based features and infrastructure.
• Build robust evaluation systems for AI tools.
• Implement safety and compliance measures for user trust.

Job description

Overview

Location: London (Hybrid - 2-3 days/week in-office)

Compensation: Competitive salary + meaningful equity

Visa sponsorship: Not available

A fast-growing AI startup is on a mission to reinvent how companies manage their finances building AI tools that finance teams can actually trust, control, and use at scale.

Why This Role Is Special

Real Ownership: As a founding engineer, you'll lead the design and development of production AI systems - shaping architecture, tooling, and user experience.

Built on Solid Foundations: The platform already integrates with major accounting systems and serves thousands of users. You\'ll be building on something proven - not starting from scratch.

Meaningful Impact: Your work won\'t be an internal experiment. It\'ll directly affect how real businesses understand and manage their finances.

AI With Purpose: This isn\'t about flashy demos - it\'s about building intelligent tools that are safe, explainable, and reliable in production.

What You\'ll Be Doing

• Design & Build Production AI Systems: Architect scalable LLM-based features and infrastructure that power intelligent agents and copilots for finance teams.
• Measure What Matters: Build robust evaluation systems using curated test sets, automated checks, and CI-integrated safeguards.
• Safety & Compliance First: Implement schema validation, content filtering, authorisation controls, and circuit breakers to ensure user trust and regulatory safety.
• Optimise Retrieval-Augmented Generation (RAG): Improve document chunking, indexing, and search pipelines - with a focus on latency, precision, and cost-efficiency.

What You Bring

• A deep interest in building with AI and LLMs in real-world environments.
• A strong backend engineering foundation (4+ years), ideally with experience in TypeScript, Python, or Kotlin.
• Hands-on experience shipping LLM applications or AI agents, using tools like LangSmith, Promptfoo, TruLens, DeepEval, or Phoenix.
• Solid understanding of prompt engineering, function calling, structured outputs, and evaluation techniques.
• Experience with RAG systems, including embeddings, vector databases, and retrieval strategies.
• A strong product mindset, clear communication skills, and comfort with the pace and ambiguity of early-stage startups.
• Bonus: Experience working with sensitive business or financial data, especially with attention to security, observability, and compliance.

You\'ll Thrive If You…

• Are excited by autonomy, impact, and the chance to build a product from 0 to 1
• Want to work closely with founders and have a voice in company strategy
• Prefer thoughtful, production-grade AI over quick hacks and demos
• Care about transparency, safety, and trust in AI systems