Freelance Senior Test Engineer – Payments, API & Performance

Freelance Senior Test Engineer – Payments, API & Performance

12-Month Freelance Contract

Credit Card / Payments - Bonn

We are looking for an experienced Senior Test Engineer / Technical Test Consultant to join a major technology programme within the credit-card and payments industry.

The focus will be on technically testing high-volume transactional applications, APIs and integrations across a complex payments ecosystem.

Responsibilities

• Design and execute technical test scenarios for payment applications
• Perform System, Integration, E2E and API testing
• Validate transaction flows across multiple applications and interfaces
• Design test cases, test data and test scenarios
• Perform REST API and service-level testing
• Conduct load, performance and resilience testing
• Analyse application behaviour and identify performance bottlenecks
• Test interfaces between payment platforms and downstream systems
• Execute regression and functional testing
• Support and expand test automation
• Perform detailed defect analysis and coordinate resolution with developers
• Support continuous testing within CI/CD environments
• Produce technical test documentation and test reports

Technical Environment

• REST APIs / Postman
• JMeter / LoadRunner / Gatling
• SQL
• GitLab
• CI/CD / DevOps
• Microservices

Required Experience

• Strong hands-on software testing / test engineering background
• Integration and E2E testing experience
• API / REST testing
• Load and performance testing
• Experience with complex transactional systems
• Banking, fintech, credit-card or payments experience highly desirable
• Strong understanding of defect analysis and test documentation

Experience testing high-volume, business-critical financial transactions would be particularly relevant.

Contract: 12 months

Type: Freelance

Industry: Credit Cards / Payments / FinTech