Founding Senior Engineer (up to £140k)

Dex; Greater London; On-site; GBP 110,000 - 160,000; Full time

Job summary

Dex is building a proactive AI assistant in private alpha, aiming to maintain a living model of a user’s work history and act on their behalf. The Founding Senior Engineer will own desktop app, backend, and algorithms, collaborating directly with AI researchers in a small, high-calibre team.

The role emphasizes building, not just integrating, with end-to-end ownership across the stack and a hands-on leadership style. London-based in-person work five days a week.

Qualifications

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

Responsibilities

• Build and own the desktop application, front and back end.
• Develop core algorithms bridging the AI model and user actions.
• Design and implement backend systems for continuous data ingestion and model maintenance.
• Work with AI engineers to translate research into product features.
• Drive architectural decisions across the full stack from UI to data persistence.

Skills

TypeScript

Python

Rust

C++

System design

Education

PhD or demonstrable end-to-end project ownership

Tools

Git

Job description

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.