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 theresponsible use of approved AI tools and automationto 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 API testing (REST/SOAP) using tools such as Postman, JMeter, or equivalent testing frameworks.
• Experience working with cloud-based testing platforms including BrowserStack, Sauce Labs, Appium, or comparable services.
• Solid understanding of quality engineering tooling including Jira, Jenkins, GitHub, SonarQube, and modern CI/CD practices.
• Experience using AI-enabled tools responsibly to improve engineering productivity while maintaining appropriate human oversight, governance, accessibility, and software quality.

Bonus Points For

• Development experience using Java, Ruby, Python, or similar programming languages.
• Experience delivering performance and load testing using JMeter, LoadRunner, Performance Center, or equivalent tools.
• Exposure to cloud platforms such as AWS, Azure, OpenShift, or Tanzu/Cloud Foundry.
• Experience applying DevOps practices, Agile methodologies, and accessibility standards including WCAG/AAA.
• Interest in responsible AI, automation, and emerging quality engineering technologies to continually improve software testing and delivery.

Why Join Capco

• Deliver high-impact technology solutions for Tier 1 financial institutions.
• Work in a collaborative, flat, and entrepreneurial consulting culture.
• Access continuous learning, training, and industry certifications.
• Be part of a team shaping the future of digital financial services.
• Help shape the future of digital transformation across Financial Services & Energy.

Benefits

We offer a competitive, people-first benefits package designed to support every aspect of your life:

• Core Benefits: Discretionary bonus, competitive pension, health insurance, life insurance and critical illness cover.
• Mental Health: Easy access to CareFirst, Unmind, Aviva consultations, and in-house first aiders.
• Family-Friendly: Maternity, adoption, shared parental leave, plus paid leave for sickness, pregnancy loss, fertility treatment, menopause, and bereavement.
• Family Care: Eight complimentary backup care sessions for emergency childcare or elder care.
• Holiday Flexibility: Five weeks of annual leave with the option to buy or sell holiday days based on your needs.
• Continuous Learning: Your growth, your way-minimum 40 hours of training annually through workshops, certifications, and e-learning. You'll also be assigned a Business Coach from Day One to support your professional development.
• Healthcare Access: Convenient online GP services.
• Extra Perks: Wellhub (Gympass), travel insurance, Tastecard, season ticket loans, Cycle to Work, and dental insurance.

Inclusion at Capco

We're committed to making our recruitment process accessible and straightforward for everyone. If you need any adjustments at any stage, just let us know-we'll be happy to help. We value each person's unique perspective and contribution. At Capco, we believe that being yourself is your greatest strength. Our #BeYourselfAtWork culture encourages individuality and collaboration-a mindset that shapes how we work with clients and each other every day.

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