Contract Senior Java Developer – Data/Marketmaking

In this contract role, you will build and enhance Java backend services that power trading and data workflows. You will own Python-based data ingestion tasks to support the data platform and work with PostgreSQL for data validation and queries. You’ll contribute to reliability through monitoring, logging and CI/CD, and collaborate across a lean team to deliver high-impact tooling for the business. This position offers broader scope than pure app development, with meaningful exposure to data feeding the platform. You’ll join a growing data-focused team that supports market-making activities in London.

• Build and enhance Java backend services (APIs, batch jobs, integrations) used across the business
• Write clean, testable code with solid engineering discipline (testing, code review, debugging, production support)
• Maintain and extend Python-based ingestion/ETL
• Work with PostgreSQL (schemas, migrations, performant queries, data validation)
• Improve service reliability: monitoring/logging, sensible alerting, and predictable deployments via CI/CD

• 10+ years of experience building production systems (or equivalent ability)
• Strong Java fundamentals (OO design, APIs/services, concurrency basics, testing)
• Some UI development
• comfortable with SQL/PostgreSQL
• Some Python experience (enough to manage and improve existing ETL/ingestion)

• Java
• Python
• AWS
• PostgreSQL
• Git
• CI/CD