Connecting clients to markets – and talent to opportunity.

With 5,400+ employees and over 80,000 institutional, commercial, and payments clients, we operate from more than 80 offices spread across six continents. As a Fortune 100, Nasdaq-listed provider, we connect clients to the global markets – focusing on innovation, human connection, and providing world-class products and services to all types of investors.

Whether you want to forge a career connecting our retail clients to potential trading opportunities, or ingrain yourself in the world of institutional investing, StoneX Group is made up of four business segments that offer endless potential for progression and growth.

Corporate Functions Engage in a deep variety of business-critical activities that keep our company running efficiently. From strategic marketing and financial management to human resources and operational oversight, you’ll have the opportunity to optimize processes and implement game-changing policies.

Position Purpose :

We are looking for a hands-on Senior QA Automation Engineer to join our NeXus Core backend team. You will own and improve automated testing for distributed services supporting accounts, balances, trades and positions. Working closely with engineers, product and DevOps, you will build reliable component, integration, end-to-end and performance coverage, identify quality risks early, and help the team deliver correct, resilient services. This is a coding-focused role with technical ownership, code review and mentoring responsibilities.

Primary responsibilities include

• Own the backend test strategy, prioritising by business risk and choosing appropriate component, integration and end-to-end coverage.
• Extend shared TypeScript automation frameworks and reusable helpers; build maintainable suites, deterministic test data and isolated component environments.
• Validate gRPC contracts and behaviour, including authentication, authorisation, errors, deadlines, streaming and backward compatibility.
• Test Kafka-driven ingestion and processing, including eventual consistency, duplicate or out-of-order events, retries, recovery and reconciliation with database state.
• Develop and maintain k6 performance suites; investigate latency, throughput, error rates and resource behaviour using Datadog.
• Integrate functional and performance tests into Azure DevOps pipelines; diagnose failures, improve feedback and reduce flaky tests.
• Maintain TestRail traceability and automated reporting; communicate meaningful coverage gaps, defects and release risks.
• Work with engineers and product on acceptance criteria and testability; drive defect investigation through resolution.
• Review automation pull requests, mentor QA engineers and lead practical improvements to shared tooling and testing practices.

To Land this role

• 5+ years of QA automation experience, with a strong backend/API focus and demonstrated independent ownership of automation frameworks or substantial test suites.
• Strong hands-on TypeScript / JavaScript skills: writing reusable test code, reviewing changes and debugging asynchronous behaviour. Experience with Mocha / Chai or comparable frameworks.
• Practical experience testing gRPC / Protocol Buffers, including client setup, metadata, status codes and service contracts; a solid understanding of REST API testing.
• Experience designing component and integration tests using controlled fixtures, mocks or service simulation, alongside end-to-end coverage.
• Experience testing Kafka or comparable event-driven systems, with an understanding of asynchronous processing, eventual consistency, retries and idempotency.
• Strong SQL skills for validating persisted data and investigating discrepancies; experience with PostgreSQL or a comparable relational database.
• Hands-on performance testing experience using k6 or a comparable tool, including workload design, interpreting results and investigating regressions.
• Experience running tests in Docker-based environments and integrating automation into CI/CD pipelines; confident use of Git and pull-request workflows.
• Ability to diagnose failures across tests, service logs, APIs, messaging and databases, distinguishing product defects from environment or test issues.
• Clear communication of quality risks and release confidence, effective collaboration across teams, and experience reviewing test code or mentoring other QA engineers.

Nice to Have

• Experience with our specific tooling: Azure DevOps, Docker Compose, WireMock, TestRail, Allure and Datadog.
• Familiarity with Java / Spring Boot code, Kubernetes deployments, health/readiness checks and service recovery scenarios.
• Experience validating schema evolution, API compatibility and authentication/authorisation across distributed services.
• Domain knowledge in financial services, trading systems or regulated environments, particularly account, balance, trade or position data.

Working Environment

4 days from office