Contract Senior Java Developer – Data
Summary
Contract Senior Java Developer in London building and scaling Java backend services (APIs, batch jobs, integrations) for a data platform, plus lighter Python ETL work feeding PostgreSQL. Day to day involves testing, code reviews, monitoring, alerting, CI/CD, and production support.
Overview
In this contract role you will build and enhance Java backend services that power the data platform, while owning lighter Python ETL tasks to feed PostgreSQL data stores. You will work closely with a lean team to improve reliability through testing, monitoring, and CI/CD. The role blends production Java development with data ingestion, offering impact across the firm’s data-driven infrastructure. You will scale and stabilise services that support data pipelines and analytics.
Responsibilities
- Develop and improve Java backend services, including APIs, batch jobs, and integrations
- Write clean, testable code with emphasis on testing, code reviews, and debugging
- Maintain and extend Python-based ingestion/ETL pipelines
- Work with PostgreSQL, focusing on schemas, migrations, and data validation
- Enhance service reliability through monitoring, logging, alerting, and CI/CD deployments
- Collaborate with cross-functional teams to support data-driven platforms
- Contribute to production support and incident response
Key requirements
- 10+ years of experience building production systems (or equivalent)
- Strong Java fundamentals: OO design, APIs/services, concurrency, testing
- Some UI development experience
- Comfortable with SQL/PostgreSQL
- Some Python experience for ETL/ingestion
- Familiarity with AWS and CI/CD practices
- problem-solving mindset
- team collaboration
- strong engineering discipline
- Java
- Python
- AWS