Integration QA Engineer

About Leadex Systems: Leadex Systems is a niche software consulting company and a long-time MuleSoft partner. We provide best-in-class API Management solutions in the Middle East and Europe. Our team of 66 like-minded professionals combines technical expertise with domain knowledge in digital banking, finance, and e-commerce. We embrace proactiveness, continuous learning, team spirit, and commitment to customer success. About the project: You will be joining a greenfield Fintech project developed from the ground up for a UK-based client . You will work within a high-performing cross-functional team including a Project Manager, Salesforce Lead & Developers, and a dedicated team of MuleSoft Developers. About the role: We are looking for a Back-end specialist who lives and breathes integrations. Your focus will not be on UI or internal microservices communication, but on the complex orchestration between our core platform and external third-party services (payment gateways, KYC providers, banking APIs, etc.). Responsibilities: End-to-end integration testing: Plan and execute complex test scenarios for API flows, focusing specifically on how our system interacts with external third-party providers. Data integrity and mapping: Validate data accuracy and transformation as it moves across various external services and the MuleSoft/Salesforce ecosystem. Backend validation: Perform deep-dive testing of REST/SOAP APIs, ensuring error handling, rate limiting, and edge cases for third-party integrations are robust. Defect orchestration: Identify, document, and track bottlenecks and bugs, working closely with MuleSoft developers and Salesforce architects to resolve integration gaps. Process architecture: Since this is a "from-scratch" project, you will help design and refine the end-to-end testing strategy, including regression suites and integration workflows. Stakeholder collaboration: Engage directly with UK-based client stakeholders to align on integration requirements and provide transparent reporting on quality metrics. Requirements: 3+ years of QA experience with a heavy focus on Back-end, System, and Integration testing. Integration specialist: Proven track record of testing third-party service integrations (External APIs, Webhooks, etc.). Technical toolkit: Expert-level proficiency with Postman , SoapUI, or similar API testing tools. Data proficiency: Strong SQL skills for data verification and backend state validation. Fintech mindset: Understanding of data security and the high stakes of financial transaction flows. Self-starter: Experience working on "zero-to-one" projects where processes need to be built, not just followed. Communication: Confident spoken English (B2+ level) for active participation in meetings with the British client. Bonus: Familiarity with MuleSoft, Salesforce, or the UK Fintech ecosystem is a significant plus. We offer: Flexible work schedule. 31 days of vacation. 5 sick days. Sport compensation. Support with purchasing the necessary equipment. Let's get to know each other!