Founding Senior Engineer (up to £140k)

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

Job summary

Dex is partnering with a private alpha project to build a proactive AI assistant that maintains a living model of a user’s work history. As Founding Senior Engineer, you’ll own the desktop application, backend, and algorithms, collaborating directly with AI researchers in a small, high-calibre team.

This role is hands-on: ship robust features from research to production, define scope, and drive architectural decisions across the entire stack.

Qualifications

• PhD or demonstrable ownership of a hard, end-to-end technical project.
• 5+ years building complex, comparable systems.
• Strong in TS, Python, Rust, or C++, with ability to learn new languages.

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 data ingestion and model maintenance.
• Collaborate with AI engineers to translate research into robust features.
• Drive architectural decisions across the stack from UI to data persistence.

Skills

Languages: TypeScript/Python/Rust/C++

End-to-end ownership

Cloud infrastructure

SQL/NoSQL databases

Education

PhD

End-to-end project ownership

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.

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