Location: Belgium (Mechelen)Start Date: February 2026 (ASAP)Contract Type: FreelanceWorkload: FulltimeOffice Days: Monday & Thursday
About the RoleOne of our clients is looking for a highly skilled Freelance Performance Tester with strong UI automation and API testing expertise. The role is based onsite in Mechelen. They are seeking a senior performance testing specialist capable of designing, scripting, executing, and analysing performance tests across web, mobile, and API-driven applications. The ideal consultant brings deep technical knowledge, a proactive mindset, and excellent communication skills.
Key ResponsibilitiesScript end-to-end UI user flows for web and mobile applications using Apache JMeterDesign, develop, and execute comprehensive performance test scenarios for web, API, and mobile applicationsMaintain clear traceability between test scenarios, scripts, and Non-Functional Requirements (NFRs)Prepare and manage performance test data, including dataset creation and supporting teams with data needsWork with standalone and distributed JMeter environments, including Docker-based setupsExecute load, stress, volume, and endurance testsCollect detailed technical input from developers and solution architectsBuild realistic workload models, gather stakeholder feedback, and secure approval before executionProduce performance test execution reports using JMeter Dashboards, including deep-dive analysis and recommendationsUse monitoring and observability tools such as Dynatrace for analysis and troubleshootingDefine environmental scalability and extrapolation aligned with production environmentsTake ownership of performance scripts and maintain existing assetsRegister, track, and follow up on performance-related defects with development teamsProvide structured progress reporting to the Delivery Manager and maintain accurate status in Jira
Required Skills & ExperienceMinimum 5+ years of hands-on performance testing experienceStrong scripting skills ( Java )Solid experience with Apache JMeter for UI and API performance testingStrong analytical mindset, attention to detail, and technical autonomyExcellent communication skills in English and DutchAbility to work independently in a complex technical environment
EducationBachelor's or Master's degree in Computer Science, ICT/IT, or a related technical field
Nice to HaveExperience in a telecommunications environmentKnowledge of CI/CD pipeline integration for performance testingFamiliarity with additional monitoring or performance analysis tools