Senior QA Engineer

About Ceffu Ceffu is a leading institutional-grade digital asset custody platform, offering secure, compliant, and scalable solutions for enterprises, hedge funds, and financial institutions.  Our mission is to provide cutting-edge security and infrastructure to support the seamless integration of blockchain technology into institutional finance. Job Responsibilities Design, develop, and maintain comprehensive test strategies, test plans, and test cases for backend services and distributed systems. Take ownership of quality assurance throughout the software development lifecycle, including requirement analysis, test design, implementation, testing, deployment, and production support. Design and execute functional, integration, regression, system, and end-to-end testing for backend services and business workflows. Develop and maintain automated testing frameworks and test scripts for RESTful APIs and backend services. Build comprehensive test scenarios for high-concurrency and distributed systems, with a focus on data consistency, reliability, fault tolerance, idempotency, and high availability. Test and validate APIs, database models, message-driven workflows, and system integrations to ensure stability, correctness, and efficiency. Collaborate closely with cross-functional teams to identify quality risks and deliver high-quality solutions. Conduct code and technical design reviews from a quality perspective, contribute to testing standards, and drive QA best practices across the team. Monitor production systems, troubleshoot incidents, reproduce defects, and proactively identify quality, performance, and reliability risks. Continuously improve testing efficiency by enhancing test automation, CI/CD integration, test coverage, observability, and quality processes. Lead or contribute to the development and continuous improvement of the AI engineering capabilities, tools, and infrastructure. Stay current with emerging testing technologies and share testing knowledge and best practices with the team. Skills & Experience Required Bachelor's degree in Computer Science, Software Engineering, or a related field. 5+ years of QA or software testing experience, with strong experience in backend and API testing. Solid understanding of software testing methodologies, test design, defect management, and software engineering best practices. Strong experience with API testing, including RESTful APIs, request/response validation, authentication, authorization, error handling, and boundary conditions. Hands-on experience with test automation frameworks and scripting/programming languages such as Java, Python, or similar. Strong understanding of distributed systems and testing concepts, including scalability, reliability, fault tolerance, idempotency, concurrency, data consistency, and high availability. Experience testing microservices architectures and asynchronous systems. Experience with relational databases such as MySQL or PostgreSQL, including SQL-based data validation and data integrity testing. Experience with caching technologies such as Redis. Familiarity with message queues such as Kafka, RabbitMQ, or RocketMQ, including testing asynchronous and event-driven workflows. Experience with containerization and deployment technologies such as Docker and Kubernetes. Familiarity with Git, CI/CD pipelines, and automated testing practices. Experience with performance and load testing tools such as JMeter, Gatling, Locust, or similar tools. Strong analytical, debugging, and problem-solving skills. Basic proficiency in reading and writing English. Preferred Qualifications Experience testing or developing Web3, digital wallet, digital asset custody, cryptocurrency exchange, payment, or financial transaction systems. Understanding of blockchain fundamentals, including public/private key cryptography, wallet architecture, blockchain transactions, and digital assets. Experience testing or integrating blockchain infrastructure, blockchain nodes, smart contracts, Web3 technologies, or crypto-related products. Experience testing high-throughput, low-latency backend systems. Familiarity with observability and monitoring tools such as Prometheus, Grafana, ELK, or OpenTelemetry. Experience with security testing, financial transaction testing, data consistency, and transaction integrity. Experience applying AI technologies to improve test automation, test case generation, defect analysis, or engineering productivity is a plus.