Founding Senior Engineer (up to £140k)

Dex; Greater London; On-site; GBP 120,000 - 180,000; Full time

Job summary

Dex is partnering to place you in a founding senior engineer role aimed at building a proactive AI assistant from the ground up. You will own desktop, backend, and algorithmic development, working directly with AI researchers in a small, high-caliber team.

This is a rare chance to define your scope, not inherit it, developing a complex system from first principles and shipping robust features in a hands-on environment in London, five days a week.

Qualifications

• A PhD or demonstrable personal ownership of a hard, end-to-end technical project.
• 5+ years building complex, comparable systems, solving genuinely hard problems.
• Strong in TypeScript, Python, Rust, or C++, with a proven ability to quickly master new languages.
• Experience owning the full engineering lifecycle: shipping robust products, working from user requests, and ideally running scientific processes.
• Comfortable with cloud infrastructure, SQL/NoSQL databases, and self-organising in an ambiguous environment.
• Willingness to work in person in London (Elephant and Castle) five days a week.

Responsibilities

• Build and own the desktop application, front and back end.
• Develop core algorithms that bridge the AI model and user actions.
• Design and implement the backend systems for continuous data ingestion and model maintenance.
• Work directly with AI engineers, translating research into robust, shippable product features.
• Drive architectural decisions across the entire stack, from user interface to data persistence.

Skills

TypeScript

Python

Rust

C++

Cloud infrastructure

SQL/NoSQL databases

End-to-end ownership

Education

PhD or demonstrable ownership of a hard, end-to-end technical project

Job description

This role is with one of Dex's trusted partner companies. We work closely with their teams to truly understand their culture, goals, and what they're looking for, so we can match you with the right opportunity and give you context about the role before you commit to a process.

Dex is an AI recruiter agent that helps you run your job search. Tell Dex your stack, seniority, and what you want to build. We will manage your applications and surface other opportunities that are a fit.

The role

This team is building a truly proactive AI assistant. Not a chatbot, but an agent that maintains a living model of a user's entire work history - emails, messages, documents - to anticipate needs and act on their behalf. They are in private alpha with early customers, backed by leading investors, and founded by a small group of repeat founders with deep technical backgrounds.

As a Founding Senior Engineer, you won't own a slice of the stack. You'll manage the whole thing: desktop application, backend, and algorithmic development, working directly with AI researchers. This is a chance to define your scope, not inherit it, building a complex system from first principles in a small, high-calibre team. It's for engineers who want to build, not just integrate.

The work

• Build and own the desktop application, front and back end.
• Develop core algorithms that bridge the AI model and user actions.
• Design and implement the backend systems for continuous data ingestion and model maintenance.
• Work directly with AI engineers, translating research into robust, shippable product features.
• Drive architectural decisions across the entire stack, from user interface to data persistence.

What You Bring

• A PhD or demonstrable personal ownership of a hard, end-to-end technical project.
• 5+ years building complex, comparable systems, solving genuinely hard problems.
• Strong in TypeScript, Python, Rust, or C++, with a proven ability to quickly master new languages.
• Experience owning the full engineering lifecycle: shipping robust products, working from user requests, and ideally running scientific processes.
• Comfortable with cloud infrastructure, SQL/NoSQL databases, and self-organising in an ambiguous environment.
• Willingness to work in person in London (Elephant and Castle) five days a week.

Why apply through Dex

This is a rare founding role at a company building genuinely novel AI. Opportunities like this are often oversubscribed or hard to find. Apply through Dex to get a full brief on the company and role, skip the cold application process, and explore other similar high-impact positions.

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