Senior Application Tester – API & Event‑Driven Testing

About the role

Keystone Solutions is looking for an Expert Application Tester to join a client‑site consultancy mission. The client is modernising a legacy revenue and collections platform into a micro‑services architecture on Kubernetes, adopting an API‑first and event‑driven approach. You will work closely with the client’s teams to ensure the new platform meets functional, performance and regulatory expectations.

Key responsibilities

• Prepare test plans, design detailed test cases and document defects, working on‑site or in a hybrid model.
• Execute API testing for REST services, validating OpenAPI specifications, idempotency, pagination, versioning, error handling, JSON payloads and dead‑letter queue processing.
• Apply Behaviour‑Driven Development (BDD) by writing Gherkin scenarios that align with acceptance criteria.
• Perform exploratory testing, identify edge cases and assess usability from an end‑user perspective.
• Test event‑driven integrations and message queues such as ActiveMQ and RabbitMQ, covering functional and resilience aspects.
• Participate in Agile/Scrum ceremonies, continuously improve testing practices and coach teams on quality standards.
• Communicate test results, risks and quality metrics to developers, analysts, QA leads and management.
• Design test data, automation strategies and contribute to UI/API automation using Playwright and Selenium.
• Use Jira, Confluence and Xray for requirement traceability, test execution and reporting.

Required profile

• Extensive experience in application testing within Agile environments.
• Strong analytical mindset with the ability to think critically and adopt an end‑user perspective.
• Proven capability to coach and mentor testing teams.
• Excellent communication skills for reporting quality status to diverse stakeholders.

Required skills

• API testing (REST, OpenAPI)
• Behaviour‑Driven Development (BDD) and Gherkin
• Message‑queue testing (ActiveMQ, RabbitMQ)
• Agile/Scrum methodologies
• Jira, Confluence, Xray
• UI and API automation tools (Playwright, Selenium)