Contract Senior Java Developer – Data
Contract Senior Java Developer – Data
Up to £700 per day Outside IR35 (6 month rolling)
In office – City of London
Quant Capital is hiring for a small, high-performing market maker in London. This is a junior-to-mid role focused primarily on Java development, with a secondary responsibility owning straightforward Python ETL/data ingestion into AWS and PostgreSQL. This is a growing team focused on data ingestion and building tooling for the wider firm.
What you’ll do:
- 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 (pragmatic plumbing, not heavy data engineering)
- Work with PostgreSQL (schemas, migrations, performant queries, data validation)
- Improve service reliability: monitoring/logging, sensible alerting, and predictable deployments via CI/CD
Tech:
Java (primary), Python (secondary), AWS, PostgreSQL + Git, CI/CD, logging/monitoring
What they want:
- 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)
Nice to have
- Any finance or markets exposure
- Familiarity with common AWS patterns for running services and pipelines
Why this role
- Broader scope than pure app dev: you’ll understand the data feeding the platform
- Lean team, high impact, strong growth runway