Senior Backend Engineer (up to £175k)

Dex; Greater London; On-site; GBP 140,000 - 190,000; Full time

Job summary

Dex is building an AI workspace for sensitive financial data with SOC 2, GDPR, and FCA compliance. Join a lean senior backend team, owning end-to-end critical systems and data pipelines while working closely with founders.

You will architect scalable services, optimize databases, and collaborate with ML teams to productionise models, helping the platform scale and influence engineering culture.

Qualifications

• 7+ years of backend engineering experience in production systems.
• Expert-level Python with FastAPI and PostgreSQL tuning.
• Experience with event-driven architectures and brokers like Kafka/Celery.
• Strong cloud, Docker/Kubernetes, and security fundamentals.
• Experience in regulated environments (SOC 2, GDPR, FCA) is a plus.

Responsibilities

• Architect and build scalable backend services and APIs for an AI workspace handling sensitive data.
• Design and implement high-performance data pipelines for large financial datasets.
• Optimise PostgreSQL schemas, queries, and indexing for high throughput.
• Collaborate with ML engineers to productionise models in robust backends.
• Lead design reviews, mentor engineers, and shape engineering culture at scale.

Skills

Python

FastAPI

PostgreSQL

Query optimisation

Distributed systems

Cloud platforms

Docker/Kubernetes

Security

Event-driven architectures

Kafka

Tools

Docker

Kubernetes

Azure

Job description

The role

This company builds an AI workspace for sensitive financial data, serving some of the world's largest regulated institutions. Think workloads where SOC 2, GDPR, and FCA compliance aren't just buzzwords, but fundamental to the product. They've secured significant Series A funding from leading investors and are scaling fast.

You'll join a lean, senior backend team, reporting directly to the founders, at the intersection of AI and finance. This is a staff-track IC seat with visible influence, architecting core services and data pipelines. It's for an engineer who wants to own critical systems end-to-end, not just maintain a small component of a larger platform.

The work

• Architect and build scalable backend services and APIs for an AI workspace handling sensitive financial data.
• Design and implement high-performance data pipelines to process large-scale financial datasets with strict accuracy and latency requirements.
• Optimise database schemas, queries, and indexing strategies for PostgreSQL in a high-throughput, distributed environment.
• Partner with ML engineers to productionise models, integrating them seamlessly into robust backend systems.
• Lead technical design reviews, mentor engineers, and contribute to shaping the engineering culture as the platform scales.

What You Bring

• 7+ years of backend engineering experience, with a track record of building and scaling production systems.
• Expert-level Python, modern web frameworks (FastAPI), and deep expertise in PostgreSQL query optimisation and scaling.
• Experience with event-driven architectures, message brokers (e.g., Celery, Kafka), and designing clean REST APIs and microservices.
• Strong fundamentals in distributed systems, cloud platforms (Azure preferred), Docker/Kubernetes, and security (authn/authz, encryption).
• Experience shipping software in regulated environments (SOC 2, GDPR, FCA) is a significant advantage.