Principal Java Developer - Contractor/Remote

ThinkMarkets is a global financial technology company, specializing in providing multi-asset trading solutions to thousands of clients around the world. With our flagship ThinkTrader platform, we make it available for our clients to trade the world 24-hours a day. Our mission is to bridge the gap between traders, investors, and platforms by allowing access to global markets and thousands of products thus providing our clients the ability to trade the world in the palm of their hand. We use the latest technologies to give traders seamless access to our proprietary trading platforms.

We are looking for a senior-level Java engineer who thrives in complex environments and wants to elevate the engineering bar within a multidisciplinary trading platform ecosystem.

This is not a traditional Java developer role. You will be working on cutting-edge architecture initiatives, rewriting monolithic systems into modular microservices, and integrating AI-assisted development into daily workflows using our proprietary LLM agent, Windsurf.

This role is fully remote (EU time zones preferred), contractor-based, and highly autonomous. You’ll be the go-to expert for complex backend solutions and an engineering force multiplier across teams that are currently focused on feature-level development and integrations.

Responsibilities

• Lead the development and decomposition of legacy monoliths into scalable, resilient Java-based microservices.
• Review and refactor AI-generated code from Windsurf, ensuring accuracy, performance, and maintainability.
• Own critical backend services end-to-end including design, testing, deployment, and documentation.
• Collaborate closely with architects, DevOps, and platform leads to set modern engineering standards.
• Mentor and support mid-level engineers by bringing clarity, performance thinking, and clean code practices.
• Participate in design reviews, API definition, and build out of messaging-based systems (Kafka, RabbitMQ).

Requirements

• 7+ years of backend Java development, ideally in fintech, trading, or low-latency/high-availability systems.
• Expertise in Java 11+, Spring Boot, microservice design patterns, and system decomposition strategies.
• Strong understanding of multithreading, memory management, distributed transactions, and security.
• Familiarity with code generation workflows, AI copilots, or prompt engineering (e.g. ChatGPT, GitHub Copilot).
• Deep experience with CI/CD pipelines, containerized environments (Docker, Kubernetes), and observability stacks.
• Ability to critically evaluate and improve AI-generated code for correctness, scalability, and clarity.
• Strong communication skills and ability to drive projects forward independently and collaboratively.

Preferred Qualifications

• Experience working with LLM-based tools or contributing to AI-driven developer platforms.
• Familiarity with FIX protocol and real-time data distribution in financial systems.
• Experience with domain-driven design, event-driven architecture, and reactive programming (e.g. Reactor, Vert.x).