Senior Java Backend Engineer for Payments & Microservices

VASS UK&I; Greater London; On-site; GBP 90,000 - 130,000; Part time

Job summary

VASS UK&I in London is seeking an experienced Senior Java Software Engineer to join a team developing and supporting modern payment-processing systems. This six-month contract role focuses on building secure, scalable backend applications with Java, Spring Boot, and microservices.

You will connect systems via APIs and messaging, monitor performance, resolve complex issues, and promote engineering best practices while delivering reliable production-ready solutions.

Qualifications

• Five+ years of software development experience using Java
• Experience with Spring Boot and microservices
• Experience with messaging systems like Kafka and RabbitMQ/IBM MQ
• Experience integrating APIs using REST and GraphQL
• Knowledge of relational and non-relational databases
• Strong analytical and logical reasoning skills
• Proactive approach and ability to learn quickly
• Bachelor's degree in a related field such as systems/engineering, math or tech
• Knowledge of UK/international payment standards (ISO 20022, SWIFT, MX)
• Experience with Docker and Kubernetes
• Knowledge of AWS or another cloud platform
• Experience with performance-testing tools (Gatling or JMeter)
• Familiarity with Jira and Confluence
• DevOps/CI using Gradle, GitHub Actions, Sonar

Responsibilities

• Developing and maintaining payment systems and platform services
• Building microservices, middleware applications, orchestrators, and automated tests
• Integrating systems through APIs and messaging technologies
• Providing technical guidance and promoting software engineering best practices
• Overseeing application monitoring and supporting production implementations
• Providing third-line support for complex application issues
• Improving application performance, observability, and resilience
• Working proactively within an agile development environment

Skills

Java

Spring Boot

Microservices

REST

GraphQL

Databases (SQL/NoSQL)

Analytical thinking

Proactive learner

Jira/Confluence

CI/CD (Gradle/GitHub Actions/Sonar)

Education

Bachelor's degree in Systems/Computer Engineering or related

Tools

Kafka

RabbitMQ

Docker

Kubernetes

AWS

Gradle

GitHub Actions

Sonar

Gatling

JMeter

Jira

Confluence

Job description

VASS UK&I in London is seeking an experienced Senior Java Software Engineer to join a team developing and supporting modern payment-processing systems. This six-month contract role focuses on building secure, scalable backend applications with Java, Spring Boot, and microservices.

You will connect systems via APIs and messaging, monitor performance, resolve complex issues, and promote engineering best practices while delivering reliable production-ready solutions.