QA engineer (auto) for high-load systems

Yesim is an international eSIM provider with 7+ years of experience in delivering secure, seamless connectivity anywhere in 200 countries around the world. We specialize in fast, secure, and global connectivity through advanced eSIM mobile solutions for 3+ million active users. Our innovative app allows users to manage multiple eSIMs within a single account - allowing users to effortlessly juggle several plans and share connectivity.

• Analyse requirements, designs, and technical solutions before development begins; proactively identify ambiguities, risks, and conditions that cannot be properly tested.
• Design testing strategies and test scenarios for new and existing functionality, including functional, integration, regression, negative, and exploratory testing.
• Test backend services and REST APIs, including authentication, validation, error handling, edge cases, idempotency, and interactions between services.
• Validate data at the API, database, log, and external integration levels rather than relying solely on the user interface.
• Prepare and maintain test data, test environments, and request collections for reproducible testing.
• Document defects so that the team can reproduce them quickly, including preconditions, steps, actual and expected results, requests and responses, logs, and the impact on users or business processes.
• Perform smoke and regression testing before releases and participate in decisions regarding release readiness.
• Verify fixes in staging, monitor results after deployment to production, and participate in incident and root cause analysis.
• Establish an approach to load testing for critical APIs and business scenarios based on realistic system usage patterns.
• Select and implement an appropriate tool, such as k6, Gatling, JMeter, or Locust, based on project requirements and team capabilities.
• Design load, stress, spike, and soak testing scenarios; configure virtual users, ramp-up periods, request rates, and test duration.
• Define measurable success criteria, including throughput, error rate, average response time, p90, p95, p99, system stability, and acceptable levels of performance degradation.
• Distinguish limitations of the test environment and load generator from limitations of the system itself to ensure that results are interpreted correctly.
• Analyse results together with developers using application, database, and infrastructure logs and metrics; document conclusions, identified bottlenecks, and recommendations.
• Ensure that load tests are reproducible and can be executed in a controlled manner locally, through CI/CD, or on a dedicated runner.
• Use Playwright to automate repetitive checks and prepare a foundation for future REST API test automation.
• Determine which scenarios should be automated based on risk, execution frequency, feature stability, and maintenance cost.
• Write readable and maintainable tests, extract reusable logic, manage environment configuration and secrets, and prepare independent test data.
• Store test code and configuration in Git, work through GitHub Pull Requests, and participate in test code reviews.
• Integrate automated checks and reports into GitHub Actions as the automation suite develops.
• Participate in sprint planning, daily stand-ups, refinement sessions, and retrospectives; communicate risks, blockers, and estimate changes in advance.
• Contribute to the definition of Acceptance Criteria, Definition of Ready, and Definition of Done, ensuring that requirements are unambiguous and testable.
• Collaborate with developers when investigating defects and debugging issues, providing specific technical evidence instead of general problem descriptions.
• Keep test documentation, checklists, scenario collections, execution instructions, and quality reports up to date.
• Propose improvements to the product, test infrastructure, and engineering processes, and drive agreed improvements through to implementation.

• 4+ years of professional experience testing web applications and backend systems, including experience at Senior level or independently owning a quality assurance area.
• Strong understanding of test design techniques, risk-based testing, and regression suite development.
• Solid experience testing REST APIs, including HTTP methods and status codes, HTTP headers, cookies, JSON, multipart/form-data, authentication, pagination, and error handling.
• Hands-on experience with Postman, curl, or similar tools for API investigation and manual testing.
• Hands-on experience building load tests using at least one of the following tools: k6, Gatling, JMeter, or Locust.
• Ability to design load profiles and analyse latency, throughput, error rate, p90, p95, and p99 metrics; understanding of the differences between load, stress, spike, and soak testing.
• Experience with Playwright, with the ability to independently write, debug, and maintain API or end-to-end test scenarios.
• Basic programming skills in TypeScript or JavaScript.
• Solid SQL skills, including preparing and validating test data, reading queries, and verifying database state.
• Experience reading logs and using trace IDs or correlation IDs to track requests across services.
• Experience with Git and GitHub, including branches, commits, Pull Requests, resolving basic conflicts, and participating in code reviews.
• Understanding of Docker and CI/CD, with the ability to run a test environment or test suite locally and investigate pipeline failures.
• Ability to clearly communicate defects, risks, and test results to both developers and non-technical stakeholders.
• English at a professional working level for documentation, written communication, and technical discussions.
• Russian at a minimum B2 level, as it is used for internal team communication.
• Будет плюсом: Experience testing high-load systems, payment flows, or critical external integrations; Experience with Grafana, Kibana, Sentry, Prometheus, ClickHouse, or similar observability tools; Experience analysing MySQL or MariaDB performance and understanding how queries, indexes, and locks affect API response times; Experience in telecommunications, eSIM, or SaaS products; Knowledge of API security fundamentals, including secret management, rate limiting, access control, and the OWASP API Security Top 10; Knowledge of ISO 27001 or experience working in an environment with enhanced security requirements; Experience configuring tests and publishing reports in GitHub Actions

• A fully remote setup — work from anywhere in the world.
• An international team that values creativity and initiative.
• Ownership of complex features and components from day one.
• Ownership of the quality and performance testing direction.
• Autonomy in establishing the load testing practice and selecting a practical approach to test automation.
• Direct collaboration with the Backend Tech Lead and CDO - your conclusions and recommendations will contribute to technical and product decisions.
• An opportunity to contribute to the development of our engineering culture, testing tools, and product delivery processes.
• Company-sponsored English language training.