Principal Engineer

Jack & Jill/External ATS; Greater London; On-site; GBP 80,000 - 110,000; Full time

Job summary

A fast-growing AI automation startup in London is seeking a Principal Engineer to lead the technical direction and evolve the platform architecture. In this role, you will design and implement sophisticated LLM integrations while working closely with customers to develop reliable, automated solutions. The ideal candidate has extensive full-stack experience with TypeScript, expertise in AI engineering, and an entrepreneurial spirit. Join a unique opportunity to influence an innovative platform without corporate bureaucracy.

Qualifications

• Extensive full-stack experience with TypeScript and willingness to work with PHP/Laravel.
• Deep expertise in AI engineering and managing LLM APIs.
• Entrepreneurial spirit for driving the company's growth.

Responsibilities

• Own the technical direction of platform architecture.
• Design and implement sophisticated LLM integrations.
• Collaborate closely with customers to develop automated technical solutions.

Skills

Full-stack experience with TypeScript

Experience with PHP/Laravel

Managing LLM APIs

Real-time streaming interfaces

Job description

This is a job that Jill, our AI Recruiter, is recruiting for on behalf of one of our customers. She will pick the best candidates from Jack's network. The next step is to speak to Jack.

Principal Engineer

Company Description: Fast-growing AI automation startup

Job Description: You will lead the evolution of a platform that transitions non-technical teams to agent-led workflows. As a key technical leader, you will bridge the gap between complex AI capabilities and intuitive user experiences. This role involves making pragmatic architectural decisions while remaining hands‑on to ensure systems are reliable, scalable, and customer‑centric.

Location: London, UK

Why this role is remarkable:

• Work directly with award‑winning founders who have multiple successful exits and a proven track record of scaling to acquisition.
• Join a well‑funded venture that has already secured top‑tier backing and established a solid base of paying customers.
• Influence the zero‑to‑one journey of a robust AI platform without the friction of corporate bureaucracy or management‑heavy layers.

What you will do:

• Own the technical direction and evolve the platform architecture to support scaling agent‑powered systems.
• Design and implement sophisticated LLM integrations focusing on prompt engineering, token management, and streaming reliability.
• Collaborate closely with customers to translate real‑world behavioral challenges into reliable, automated technical solutions.

The ideal candidate:

• Extensive full‑stack experience with TypeScript and a willingness to work across modern web stacks including PHP/Laravel.
• Deep expertise in AI engineering, specifically managing LLM APIs, context windows, and real‑time streaming interfaces.
• Entrepreneurial spirit with a desire to take ownership of non‑engineering tasks to drive the company's growth forward.

Next steps

1. Visit our website.
2. Click "Talk to Jack".
3. Talk to Jack so he can understand your experience and ambitions.
4. Jack will make sure Jill (the AI agent working for the company) considers you for this role.
5. If Jill thinks you're a great fit and her client wants to meet you, they will make the introduction.
6. If not, Jack will find you excellent alternatives. All for free.