Senior Software Engineer

djr; Watford; On-site; GBP 92,000 - 129,000; Full time

Job summary

djr is seeking an experienced Senior Python Backend Engineer to join on a 4-month contract. The role focuses on hands-on development of production backend services, using FastAPI and modern Python patterns.

You will design, build and improve scalable REST APIs and distributed systems, work with Kafka or RabbitMQ, debug production code, and contribute to code quality alongside senior backend engineers.

Qualifications

• Experience designing and maintaining production REST APIs.
• Hands-on design, build and improvement of production backend services.
• Comfortable debugging and improving existing production code.

Responsibilities

• Designing and building production Python backend services using FastAPI.
• Developing scalable REST APIs and distributed backend systems.
• Working with event-driven architectures using Kafka or RabbitMQ.
• Improving performance, reliability and maintainability of existing services.
• Collaborating with experienced backend engineers on architecture and code quality.

Skills

Strong SQL knowledge

Distributed systems design

REST API design

Production backend experience

Debugging production code

Tools

FastAPI

Kafka

RabbitMQ

Docker

SQLAlchemy

Pytest

Job description

We're working with a technology company building high-performance backend platforms, and we're looking for an experienced Senior Python Backend Engineer to join the team on an initial 4-month contract.

This is a hands-on engineering role focused on designing, building and improving production backend services.

This is NOT an AI, Data Engineering or Cloud Engineering position.

What you'll be doing

• Designing and building production Python backend services using FastAPI
• Developing scalable REST APIs and distributed backend systems
• Working with event-driven architectures using technologies such as Kafka or RabbitMQ
• Improving performance, reliability and maintainability of existing services
• Collaborating with experienced backend engineers on architecture and code quality

What we're looking for

• Commercial experience with FastAPI (or extensive modern Python API development)
• Experience designing and maintaining production REST APIs
• Background working with microservices and distributed systems
• Experience with messaging technologies such as Kafka, RabbitMQ or similar
• Strong SQL/database knowledge
• Experience with Pytest and automated testing
• Comfortable debugging and improving existing production code

Nice to have

• Docker
• SQLAlchemy
• Time-series or event-driven platforms

This role isn't right if...

• Your recent experience is primarily AI / LLM / RAG / Agentic AI
• You're mainly a Data Engineer
• You're primarily a Cloud/DevOps Engineer
• You're an Architect or Manager looking for a leadership role rather than hands-on coding

We're looking for someone who enjoys solving backend engineering problems and writing production Python every day.