Junior Software Engineer (Backend & Agents)

About The Team

Dex is an AI-powered recruiter, matching exceptional software engineers with top tech companies. We're one of the fastest-growing UK startups, and have raised $3.1M from a16z and Concept Ventures to build a best-in-class voice agent, matching engine and web app experience that will redefine the way that talent and opportunity connect.

We're looking for the most ambitious graduate or junior backend engineer to join our team, building both our product and AI agent systems to truly understand our users and connect them with the best opportunities. If you’re less than 2 years since graduating and have something to prove, Dex might be the place for you.

About The Role

As a Software Engineer at Dex, you'll be a key owner of the backend systems that drive our agentic voice agent and other agents in our web application. You'll work with a modern Python stack - FastAPI, Postgres, Redis, Docker, and Pydantic AI, all running on GCP. Your focus will be split across the following areas, though you can lean into some more heavily than others depending on your interests and strengths:

Product backend: Owning key areas of our backend infrastructure - making sure new additions to product are robust, secure and scalable from day one.

Agent backend: Building and improving the infrastructure that powers our voice agent. This includes running evaluations, improving systematic information extraction, and ensuring our agentic systems run reliably at scale.

Observability: Ensuring visibility into our production systems through monitoring, logging, and performance tracking.

Matchmaking: Building and optimizing the data and systems that power our AI-driven talent matching engine.

In this role you will:

Design and build scalable backend infrastructure for AI agent workflows and product systems

Own the reliability and performance of systems that power our voice agent and web application

Work with the team to define technical strategy, architecture, and long-term goals

Build and maintain robust APIs, authentication systems, and database architecture

Collaborate with product, design, and other engineers to build infrastructure that meets evolving needs

Contribute to the development of best practices around system reliability, performance, and delivery velocity

You might thrive in this role if you:

Are genuinely excited about what we're building

Can demonstrate backend experience in Python or similar languages, and solid CS fundamentals

Have already taken on projects using AI agents and are excited to go deeper

Take pride in writing clean, maintainable code

Are outcome-oriented and proactively take ownership of areas of the codebase

Excel at systematically breaking down complex problems and weighing up solutions pragmatically

What we offer

Joining Dex means being part of a fast-moving, ambitious team building something meaningful. In addition, we offer:

£50,000 to £80,000

Meaningful equity

Flexible working with minimum 3 days a week in our office near London Bridge

Brand-new Macbook Pro

Gym membership

An opportunity to work with and learn from an experienced team, and grow with the business

The process

Our hiring process is designed to be transparent and respectful of your time. Here’s what you can expect:

Application

• Call with Dex - we love seeing candidates try the product first, and a call with Dex can help you get clear on what you’re great at and what your perfect next role would look like.

Remote Round

• Call with Cofounder - you’ll chat directly with one of our founders to learn about our vision, what we’re building, and how you could play a key role in shaping it.

• Take-home technical test - a practical challenge designed to mirror the kind of problems we solve at Dex.

In-person Round

• Tech test review interview - You’ll walk through your take-home task with our engineers, discussing your approach, trade-offs, and thought process

• Meet the team - A casual opportunity to meet more of the people you’d be working with day to day and ask any questions you have

Offer