Software Development Engineer in Test (SDET)

We are looking for a talented and motivated Mid-Level SDET to join our growing quality engineering team. The ideal candidate will have strong hands-on experience in mobile and cross-platform test automation, a solid grounding in software development principles, and a passion for quality. You will work alongside senior engineers to design, build, and maintain test infrastructure for a range of client projects spanning iOS, Android, and web platforms., Design, develop, and maintain automated test frameworks for iOS and Android applications. Write and execute test plans, test cases, and test scripts across functional, regression, integration, and performance test areas. Build robust UI and API test automation using industry-standard tools and frameworks. Integrate automated tests into CI/CD pipelines (Jenkins, Fastlane, or equivalent). Collaborate with developers and product teams to understand requirements and define quality gates. Identify, document, and track defects through to resolution using defect management tools. Contribute to the improvement of internal testing standards, processes, and tooling. Perform exploratory testing on mobile apps across a wide range of real devices and simulators. Support test coverage for AI-powered features including evaluation pipelines and model behaviour validation. Produce clear and concise test reports and metrics for stakeholders. Technical Requirements

Proficiency in at least one of: Swift, Objective-C, Java, Kotlin, or Python for test scripting. Working knowledge of JavaScript / TypeScript for web and cross-platform test automation. Experience with testing frameworks: XCTest, XCUITest, Espresso, JUnit, or Jest. Mobile Testing Hands-on experience with iOS and/or Android test automation. Familiarity with real device testing and device farms (e.g. AWS Device Farm, BrowserStack, or equivalent). Understanding of mobile architecture patterns: MVVM, VIPER, or similar. API & Backend Testing Experience with REST API testing tools (Postman, RestAssured, or equivalent). Basic understanding of distributed systems and microservices architectures. CI / CD & DevOps Experience integrating tests within CI pipelines: Jenkins, GitHub Actions, Fastlane, or similar. Familiarity with version control (Git) and branching strategies. Performance & Debugging Ability to use profiling and debugging tools: Xcode Instruments, Android Device Monitor, Flipper, or Charles Proxy. Understanding of performance testing concepts: latency, memory, CPU, and battery impact on mobile apps. Databases Basic SQL knowledge; exposure to SQLite, CoreData, or Realm is advantageous. Desirable / Nice-to-Have Skills Experience testing design systems or shared UI component libraries. Exposure to AI/ML feature testing, prompt evaluation, or LLM output validation. Familiarity with React or cross-platform frameworks (Xamarin, React Native). Knowledge of cloud platforms: AWS or Azure for test infrastructure. Experience with macOS application testing or low-level system component testing. Background in or awareness of AR/camera feature testing on mobile platforms. Profile & Soft Skills Strong analytical mindset with a keen eye for detail and edge cases. Ability to work autonomously and manage multiple priorities in a fast-paced environment. Clear and confident communicator, comfortable engaging with technical and non-technical stakeholders. Collaborative team player with a proactive, problem-solving attitude. Comfortable with ambiguity and able to adapt quickly to new technologies and client requirements. A genuine passion for software quality and continuous improvement.

Exposure to high-profile client engagements with global technology leaders. Opportunity to work on cutting-edge AI/ML and mobile platform testing. A collaborative, expert team environment with mentorship from senior practitioners. Flexible hybrid working arrangements based in London. Continuous learning and professional development support. Competitive salary or day rate commensurate with experience.

MTEST LABS is a specialist Digital & Mobile Application Testing company founded in 2011, with offices in London and Delaware. We partner with global technology companies to deliver high-quality testing solutions across mobile platforms, AI/ML systems, and enterprise applications. Our team brings deep expertise from industry leaders including Meta, Google, Amazon, and Singapore Airlines.