Java Developer Contract

Explore Group; Greater London; Hybrid; GBP 90,000 - 150,000; Full time

Job summary

Explore Group in London is seeking a Senior Java Engineer on a contract basis to help build a greenfield fintech platform. You will design and implement low-latency, high-throughput microservices with Java 21+ and Spring Boot, owning features from architecture to production.

You will partner with product and risk teams to deliver resilient event-driven systems (Kafka/RabbitMQ) and champion TDD, automated CI/CD, and rigorous code reviews.

Qualifications

• 7+ years of deep Java expertise including Java 17/21 features, memory management, multithreading, and concurrency.
• Extensive experience with Spring Boot, Spring Cloud, and Hibernate/JPA.
• Proven track record with microservices, event-driven design (Kafka, RabbitMQ), and RESTful APIs.
• Strong relational database knowledge (PostgreSQL) alongside Redis or Hazelcast.
• Hands-on experience with AWS (EKS, Lambda, S3), Docker, Kubernetes, and Terraform.

Responsibilities

• Architect, build, and optimize scalable back-end services using Java 21+ and Spring Boot.
• Partner with product and risk teams to deliver resilient event-driven architectures.
• Drive engineering best practices, including TDD, automated CI/CD pipelines, and rigorous code reviews.
• Refactor legacy components to improve latency and system throughput.

Skills

Core Java

Java 17/21

Spring Boot

Spring Cloud

Hibernate/JPA

Microservices

Event-driven design

RESTful APIs

Kafka

RabbitMQ

PostgreSQL

Redis

Hazelcast

AWS

Docker

Kubernetes

Terraform

CI/CD

TDD

Tools

Docker

Kubernetes

Terraform

AWS

Job description

Senior Java Engineer (Contract) – Greenfield Fintech Platform

• Location: London / Hybrid (1 day/week in office)

About the Role We are seeking an exceptionally skilled Senior Java Contractor to join a high-impact team building a next-generation algorithmic trading engine. You will work on low-latency, high-throughput microservices, owning features from architecture design to production deployment.

Key Responsibilities

• Architect, build, and optimize scalable back-end services using Java 21+ and Spring Boot.
• Partner with product and risk teams to deliver resilient event-driven architectures.
• Drive engineering best practices, including TDD, automated CI/CD pipelines, and rigorous code reviews.
• Refactor legacy components to improve latency and system throughput.

Required Experience

• Core Java: 7+ years of deep expertise in Java (Java 17/21 features, memory management, multithreading, and concurrency).
• Frameworks: Extensive experience with Spring Boot, Spring Cloud, and Hibernate/JPA.
• Architecture: Proven track record with microservices, event-driven design (Kafka, RabbitMQ), and RESTful APIs.
• Database & Caching: Strong relational database knowledge (PostgreSQL) alongside Redis or Hazelcast.
• Cloud & DevOps: Hands-on experience with AWS (EKS, Lambda, S3), Docker, Kubernetes, and Terraform.

Nice to Have

• Prior domain experience in banking, fintech, or high-frequency trading.
• Familiarity with reactive programming (Project Reactor, RxJava).