Senior Quality Assurance Engineer (Event Streaming)

BUX, a modern fintech company based in Amsterdam, as a Senior Quality Assurance Engineer (Event Streaming). In this role, you will be responsible for validating the correctness, reliability, and resilience of our Kafka-based event-driven systems.

Responsibilities

• You will design, develop, and maintain automated and manual tests, execute manual and exploratory testing, and help build and mature QA processes and standards.
• You will also monitor and track key quality metrics, validate message ordering and delivery guarantees, and perform failure-mode and resilience testing.
• This is an exciting opportunity to contribute to a fast-paced, innovative company in the fintech space.
• Design, develop, and maintain automated and manual tests for Kafka-based producers, consumers, and event flows.
• Integrate automated regression, smoke, and integration test suites into CI/CD pipelines (GitHub Actions) and help build and mature QA processes.
• Monitor and track key quality metrics, test coverage, and defect trends for the streaming domain, and validate message ordering, delivery guarantees, idempotency.
• Nice-to-haves

Requirements

• Experience helping establish or mature QA processes for event-driven systems
• 5–7+ years of experience in software quality assurance, with a senior-level track record of hands-on testing in the fintech domain
• Strong knowledge of API testing (REST) and microservices/event-driven architectures
• Experience with fintech or financial services testing (financial accuracy, transactional data, regulatory compliance)
• Experience with schema registries and contract testing tools for event-driven architectures
• Excellent communication and collaboration skills with cross-functional teams
• Comfortable validating data consistency across multiple database technologies and asynchronous event flows
• Hands-on testing experience with Kafka or comparable event-streaming platforms
• Practical experience with Postman/Newman, Charles Proxy, and Xray (or similar test management tooling)

Experience working in a fast-paced Agile environment

• Hands-on experience with test automation frameworks such as Selenium and Playwright with TypeScript
• Understanding of CI/CD pipelines and integration of automated tests (GitHub Actions)
• Proficiency in at least one programming language (Java/Kotlin)

Preferred

• Experience with performance and security testing
• This role reports to the Staff QA Engineer
• Knowledge of financial regulations and compliance standards (KYC/AML)