About De Cronos Groep
De Cronos Groep is a leading Belgian technology group bringing together specialised companies and experts across software, cloud, data, digital and business transformation.
For one of our clients, we are looking for a Senior Performance Automation Engineer to strengthen a team working on business-critical and highly available systems. The assignment combines advanced test automation with performance engineering and non-functional testing.
The Role
You will design, develop and execute automation and performance-testing strategies for complex enterprise applications. The role requires a senior engineer who can work independently, build reusable test frameworks and investigate system behaviour across application, API, database, middleware and infrastructure layers.
Python and Playwright are at the core of the role. Both are essential and should be part of your day-to-day hands-on experience.
What You’ll Do
• Define, maintain and execute the overall performance-testing strategy, including baselines, success criteria and non-functional testing objectives.
• Design, develop and maintain automated testing solutions using Python and Playwright.
• Create reusable frameworks, libraries and utilities supporting functional and non-functional testing.
• Develop realistic end-to-end user journeys, workload simulations and test scenarios.
• Design and execute load, stress, soak/endurance, scalability, volume and capacity tests.
• Identify and analyse performance bottlenecks across application, API, database, middleware and infrastructure layers, and recommend improvements.
• Build and maintain performance-testing frameworks using tools such as JMeter, Locust, Gatling, LoadRunner or equivalent.
• Develop Python utilities for test-data preparation, workload modelling, result analysis, monitoring integration and automated reporting.
• Collect and interpret performance metrics including CPU, memory, network, database and application utilisation.
• Integrate automated and performance tests into Jenkins CI/CD pipelines and contribute to quality gates and release-readiness assessments.
• Use Docker and containerised environments to run repeatable test campaigns and support testing in cloud- native/distributed architectures.
• Ensure traceability between requirements, test scenarios, executions and results.
• Produce clear performance test plans, specifications, execution reports and technical recommendations.
• Work closely with developers, DevOps engineers, architects, product owners and QA engineers.
• Mentor colleagues on automation practices, performance engineering, Python standards and troubleshooting.
What We’re Looking For
• Expert-level Python, including object-oriented programming, design patterns, automation framework development, scripting, data processing and reporting.
• Expert-level Playwright, including web application automation, cross-browser testing, end-to-end automation and framework design/maintenance.
• Proven experience developing and maintaining large-scale automated testing solutions using Python and Playwright.
• Strong hands-on experience with load, stress, endurance, scalability, capacity and volume testing methodologies.
• Practical experience with at least one performance-testing tool such as JMeter, Locust, Gatling or LoadRunner.
• Strong experience integrating automated tests into Jenkins CI/CD pipelines and working with Git-based workflows.
• Experience with Docker and containerised environments.
• Strong understanding of REST APIs, web applications, distributed systems and microservices architectures.
• Proven ability to perform root-cause analysis, interpret performance metrics and produce actionable technical recommendations.
• Excellent communication and stakeholder-management skills, with the ability to work autonomously and take ownership of testing activities.
Nice to Have
• Kubernetes experience.
• Experience with Grafana, Prometheus, Elastic Stack, Dynatrace, AppDynamics or similar monitoring platforms.
• Experience with Xray, Jira and Confluence.
• Agile/Scrum experience.
• Familiarity with Site Reliability Engineering practices.
• Experience in aviation, air traffic management or another mission-critical environment.
What to Expect
• A senior hands-on engineering role with real ownership of automation and performance testing.
• A complex, business-critical environment where reliability, scalability and traceability matter.
• Close collaboration with software, DevOps, architecture and QA teams.
• A long-term client assignment through De Cronos Groep.
We connect IT professionals with projects that match their skills, professional experience, and goals, then we offer a career progression program, delivered by in-house specialists - our People Experience Partners - to guide them through our journey with us.
What we offer:
A project that matches your skills and ambitions, as well as your preferences for working policies and culture.
A competitive salary with awesome benefits and opportunities to leverage your knowledge and network to earn additional income.
An empowering and respectful work culture enriched with social and learning events.
A People Experience Partner specially assigned to you - your go-to career guide, responsible for supporting your growth, facilitating training, and ensuring your work-life balance at KWAN.
At KWAN, they make sure that I feel comfortable with the client I’m working for and that what I’m doing aligns with my career aspirations.
Luis Caldeira, DevOps @ KWAN
At KWAN, I’m given the space to be myself and do what I love. I have control over the projects I work on, as well as the direction of my career.
Pedro Fonseca, Front End Developer @ KWAN
I see my People Experience Partner as someone who is always available to provide me with motivation and constant feedback, which helps me be sure that I am in the right place.
Josimar dos Reis, Software Developer @ KWAN
I know that I’ve contributed to the growth of a company that truly values a “people first culture”, because my ideas, experiences, and individuality were always appreciated.
João Nascimento, Software Developer (KWAN Alumni)
My two years at KWAN were an incredible experience! From the start, I was welcomed into a warm and collaborative environment where I felt truly supported.
Laís Ortiz, Software Developer @ (KWAN Alumni)
Grab this opportunity, apply now!
What You Can Expect as a KWANer
Respect isn’t optional here
You’re trusted to deliver and supported to speak up.
Dedicated People Experience Partner
Someone accountable for your growth, not your allocation.
Continuous learning, built in
Learning that keeps pace with the systems you build.
Recognition that’s visible
Your impact doesn’t go unnoticed. Through our Rocket Points System, we constantly recognize your contributions.
A culture you can feel
From movie and quiz nights to dinners and our annual summer gathering, we don’t just work together - we build real connections.
Flexible spaces to work your way
Remote-first, with physical hubs when you want connection.
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