Senior Back End Engineer

Addition; City Of London; Remote; GBP 120,000 - 135,000; Full time

Benefits offered by this job

Fully remote

Job summary

Addition Solutions is seeking an experienced Backend Developer (Java/Spring Boot) for a fully remote contract. The role focuses on building scalable backend services, REST APIs and microservices in a high-volume environment. You will work with Java and Spring Boot, delivering reliable and efficient backend systems.

Prior experience in iGaming, FinTech or similar sectors is advantageous. The contract is Outside IR35, £475 per day, and runs until the end of March, with an ASAP start and fully

Qualifications

• Extensive commercial experience with Java and Spring Boot.
• Proven backend development in a microservices environment.
• Experience designing and integrating REST APIs.
• Experience with high-volume, scalable systems.
• Ability to work independently in a fast-moving remote team.

Responsibilities

• Design, develop and maintain backend services using Java and Spring Boot.
• Build and enhance microservice-based applications.
• Develop and integrate secure REST APIs.
• Support performance, reliability and scalability of high-volume systems.
• Produce clean, maintainable, well-tested code.
• Collaborate with engineers and stakeholders throughout the lifecycle.

Skills

Java

Spring Boot

REST APIs

Microservices

High-volume systems

Job description

Backend Developer - Java/Spring Boot

Start Date: ASAP

Contract Outside IR35 £475 per Day

Duration: Until the End of March

Location: Fully Remote

We're partnering with a fast‑paced, technology‑led organisation to appoint an experienced Backend Developer on a fully remote contract.

This is an excellent opportunity for a hands‑on developer with strong Java and Spring Boot experience to build and develop scalable backend systems within a high‑volume engineering environment.

We're particularly interested in candidates with previous experience in iGaming, betting, FinTech or another sector where reliability, scalability and performance are critical.

The Opportunity

As Backend Developer, you'll work as part of an established engineering team to design, develop and improve backend services and microservice‑based applications.

You'll use Java and Spring Boot to create reliable, scalable solutions, develop REST APIs and support systems handling high volumes of activity.

This is a hands‑on contract suited to someone who can work effectively at pace, contribute confidently from the outset and deliver high‑quality backend solutions within a complex technical environment.

Key Responsibilities

You'll support the development and improvement of scalable backend systems by:

• Designing, developing and maintaining backend services using Java and Spring Boot.
• Building and enhancing microservice‑based applications.
• Developing and integrating secure, reliable REST APIs.
• Supporting the performance, reliability and scalability of high‑volume systems.
• Producing clean, maintainable and well‑tested code.
• Troubleshooting backend issues and implementing effective technical solutions.
• Collaborating with other engineers and technical stakeholders throughout the development lifecycle.
• Contributing to technical discussions, code reviews and wider engineering best practices.

About You

You'll be an experienced Backend Developer with strong hands‑on Java and Spring Boot expertise and a proven ability to deliver scalable backend solutions.

You will also have:

• Strong commercial experience developing applications with Java and Spring Boot.
• Proven backend‑development experience within a microservices environment.
• Experience designing, developing and integrating REST APIs.
• Experience working with high‑volume, scalable systems.
• Strong problem‑solving and troubleshooting capabilities.
• The ability to produce clean, reliable and maintainable code.
• The confidence to work independently within a fast‑moving remote engineering environment.
• Strong communication and collaboration skills.

Experience within iGaming, betting or FinTech would be highly advantageous.

Why Apply?

This is a fantastic opportunity to contribute to the development of high‑volume backend systems within a fast‑paced engineering environment.

In return, you’ll benefit from:

• A competitive rate of £475 per day.
• An Outside IR35 engagement.
• A fully remote working arrangement.
• A contract running until the end of March.
• An immediate start.
• The opportunity to work extensively with Java, Spring Boot, microservices and REST APIs.
• Exposure to complex, scalable and high‑volume backend systems.

We are an equal opportunity employer and value diversity at our company. We do not discriminate on the basis of race, religion, colour, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status.

By applying you are confirming you are happy to be added to the Addition Solutions mailing list regarding future suitable positions. You can opt out of this at any time simply by contacting one of our consultants.