Senior Manuel Testers

Keystone Solutions is seeking an Expert Application Tester to join a consultancy mission at a client site. The client is undertaking a major modernization program within its revenue and collections administration, transforming a legacy monolithic application into a modern microservices architecture running on Kubernetes. The program follows an API-first and event-driven approach and progressively replaces the legacy platform. Beyond technical modernization, this initiative is also a business transformation program that enables new features, improves agility, and accelerates the delivery of value to both internal and external end users. By building a more flexible and scalable digital platform, the program supports better services, enhanced user experiences, and faster adaptation to continuously evolving business and regulatory needs. As a Keystone Solutions consultant, you will perform the responsibilities described below while working closely with the client's teams.

• Role level: Expert
• Most recent experience: Any time

• →Prepare comprehensive test plans, create detailed test cases, and produce clear defect descriptions, executing these responsibilities on-site or in hybrid collaboration with the client as a Keystone Solutions consultant.
• →Conduct API testing across REST and related interfaces, ensuring conformance with OpenAPI specifications and standards such as Belgif, including idempotency, pagination, versioning, error semantics, JSON payload validation, and dead-letter queue (DLQ) handling.
• →Apply Behavior-Driven Development (BDD) practices, writing and maintaining scenarios in Gherkin, and aligning tests with acceptance criteria.
• →Perform exploratory testing with strong critical thinking, identify edge cases, and consistently adopt the end-user perspective to validate functionality and usability.
• →Test event-driven and message-queuing integrations (e.g., ActiveMQ, RabbitMQ), including functional and resilience aspects.
• →Collaborate within Agile/Scrum teams, participating in ceremonies and continuously improving testing practices.
• →Coach teams on testing methodologies and best practices, helping elevate quality across squads.
• →Communicate and report software quality and risk clearly to stakeholders including developers, analysts, team leads, QA, and management.
• →Leverage sound programming logic to design robust test strategies, data setups, and automation approaches.
• →Use Jira, Confluence, and Xray to manage requirements, test design, execution, traceability, and reporting.
• →Contribute to UI and API test automation using tools such as Playwright and Selenium where appropriate.

• Agile — Level: Expert — Most recent experience: Any time
• SCRUM — Level: Expert — Most recent experience: Any time
• BDD — Level: Expert — Most recent experience: Any time
• Gherkin — Level: Expert — Most recent experience: Any time
• Coaching in the testing domain — Level: Expert — Most recent experience: Any time
• Confluence — Level: Expert — Most recent experience: Any time
• Jira — Level: Expert — Most recent experience: Any time
• Xray Tools — Level: Expert — Most recent experience: Any time
• Programming logic — Level: Expert — Most recent experience: Any time
• Prepare test plans, create test cases, and describe anomalies/defects — Level: Expert — Most recent experience: Any time
• API testing — Level: Expert — Most recent experience: Any time
• Knowledge of testing message-queuing systems (ActiveMQ, RabbitMQ, ...) — Level: Expert — Most recent experience: Any time
• Playwright — Level: Junior — Most recent experience: Any time
• Selenium — Level: Junior — Most recent experience: Any time

• Postman, SoapUI, OpenAPI, Belgif
• Idempotency, pagination, versioning, error semantics
• JSON, DLQ (dead-letter queue)

• English — Active knowledge
• Dutch or French — Nice to have

• Do you have experience clarifying functional and non-functional requirements and documenting the results of manual tests?
• Are you familiar with testing methodologies and certifications related to testing (e.g., ISTQB or others)?
• Do you have experience with exploratory testing, critical thinking, detecting edge cases, and approaching solutions from an end-user perspective?
• Are you able to communicate and clearly report software quality to various stakeholders (developers, analysts, team leads, QA, management, etc.)?

As a Keystone Solutions consultant, you will work on-site at the client (with potential hybrid collaboration as agreed) embedded in cross-functional Agile teams. You will carry out all responsibilities described in this job description under Keystone's consultancy model, partnering closely with the client's product owners, architects, developers, QA, and business stakeholders to deliver tangible value.

Joining Keystone Solutions means exposure to diverse challenges across client missions. While this engagement focuses on a large-scale modernization to microservices on Kubernetes with an API-first and event-driven architecture, future projects may span different industries, domains, and technology stacks—keeping your skills sharp and your work varied.

We invest in your growth through mentorship, peer coaching, community-of-practice sessions, and access to relevant certifications (including testing and Agile). As a consultant, you gain accelerated learning by solving real-world quality challenges, adopting modern tooling, and sharing best practices across engagements.

At Keystone Solutions, your ambition is amplified by impactful missions and clear progression paths. By delivering excellence across client projects and expanding your expertise (from BDD and API testing to event-driven and MQ testing), you build a portfolio that fast-tracks your career growth.

Being a K-Stone means you bring curiosity, ownership, craftsmanship, and client-centricity to every engagement. We uphold transparency, collaboration, and pragmatism—values that shape how we test, coach teams, and communicate quality and risk to stakeholders at each client.

This engagement offers the rare combination of business transformation and deep technical modernization: microservices on Kubernetes, API-first and event-driven patterns, and robust message-queuing. It is an excellent arena to apply BDD, strengthen API and MQ testing expertise, use tools like Jira/Confluence/Xray, and contribute to quality at scale—while coaching teams and elevating practices as a Keystone Solutions consultant.

If you are ready to tackle technical and strategic challenges in a dynamic consultancy environment, apply today at Keystone Solutions Career Portal.