Software Engineer (Backend) (up to £200k)

Dex; Greater London; On-site; GBP 85,000 - 120,000; Full time

Job summary

Dex partner company is building an AI operating system for enterprise IT, tackling complex workflows for large enterprises. You will join a lean backend team, owning core platform components and large-scale batch processing while ensuring security and observability.

You'll design the LLM gateway for token throughput and provider failover, and build internal tooling to accelerate product development. This role requires onsite collaboration with the London team five days a week.

Qualifications

• 3+ years of backend engineering experience with ownership over platform components.
• Experience designing and implementing distributed systems including queueing and batch processing.
• Familiarity with LLM infrastructure at scale: token routing, provider failover, real-time vs async patterns.
• Track record building internal tooling or APIs that significantly improve team velocity and reliability.

Responsibilities

• Design and build core backend platform components enabling rapid shipping.
• Develop and scale batch job infrastructure for massive data volumes.
• Engineer the LLM gateway, managing token throughput and provider failover.
• Establish robust auth and observability defaults for enterprise reliability and security.
• Build internal tooling and APIs that measurably accelerate product development and team efficiency.

Skills

Backend engineering

Distributed systems

LLM infrastructure

Internal tooling/APIs

Ownership & accountability

Job description

This role is with one of Dex's trusted partner companies.

This company is building an AI operating system for enterprise IT, tackling the complex problem of automating critical, complex workflows for large enterprises. They hire only engineers who can own problems end-to-end, fostering a deliberately talent-dense team where you'll learn from peers and be trusted with significant ownership from day one.

You'll join a lean backend team, owning critical platform components: large-scale batch job infrastructure, the LLM gateway for token throughput and provider failover, and the auth/observability defaults for enterprise reliability. This isn't a role for just implementing features; it's for an engineer who thrives on solving hard, foundational problems across tens of millions of lines of customer code, real-time LLM workloads, and multi-tenant security.

The work

• Design and build core backend platform components, enabling the rest of engineering to ship rapidly.
• Develop and scale batch job infrastructure handling massive data volumes and complex processing.
• Engineer the LLM gateway, managing token throughput, provider failover, and quota across diverse models and providers.
• Establish robust auth and observability defaults, meeting stringent enterprise reliability and security standards.
• Build internal tooling and APIs that measurably accelerate product development and team efficiency.

What You Bring

• 3+ years of backend engineering experience, with significant ownership over platform or infrastructure components, ideally through the MVP to scale-up phase.
• Proven experience designing and implementing distributed systems, including queueing and large-scale batch processing in production. You own problems end-to-end.
• Familiarity with LLM infrastructure at scale, including token routing, provider failover, and managing real-time vs. async patterns.
• Track record of building internal tooling or APIs that significantly improved team velocity. You treat reliability, observability, and multi-tenant security as first-class concerns.
• Ability to work in person with the team in London five days a week.