Principal Software Developer in Test (SDET)

Location: London (Hybrid) | Practice Area: Technology & Engineering | Type: Permanent

Drive test automation innovation and engineering excellence in financial technology

The Role

As a Principal Software Developer in Test (SDET) at Capco, you'll lead the strategy, architecture, and implementation of robust test automation frameworks across financial services projects. You'll work closely with cross-functional teams to deliver quality-first engineering solutions using modern testing tools and practices. You'll also mentor engineers, foster best practices in quality engineering, and help shape Capco's automation testing capability. You'll champion AI-enabled ways of working, encouraging the responsible use of approved AI and automation tools to improve engineering productivity, accelerate test delivery, and enhance software quality while ensuring appropriate governance, human oversight, and responsible AI practices.

What You'll Do

• Architect reusable, scalable test automation strategies and frameworks across web, mobile, and API platforms, applying AI-enabled engineering approaches where appropriate to improve efficiency and test coverage.
• Design, build, and maintain automated test suites for user interfaces, APIs, and backend services using modern testing frameworks.
• Integrate automated testing into CI/CD pipelines while optimising cloud-based testing platforms to support reliable and scalable software delivery.
• Lead test data management, performance and load testing, accessibility validation, and continuous quality improvement across delivery teams.
• Mentor engineers, establish testing standards, and encourage the responsible use of approved AI tools and automation to improve collaboration, productivity, and engineering quality.

What We're Looking For

• Strong experience delivering UI and mobile test automation using Selenium, WebDriver, Cucumber, Robot Framework, or similar technologies.
• Proven expertise in