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Senior Software Development Engineer in Test (SDET)

Flex - Remote - Remote - posted 2026-08-20

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Salary: USD 115,600 - 170,000 / annual

Flex is a growth-stage fintech company headquartered in NYC that is transforming rent payments by enabling users to pay throughout the month on a flexible schedule that fits their finances. As a Senior SDET, you will own test automation and quality efforts for entire product areas or major features, architecting and optimizing automation frameworks while leading test strategy for complex systems. Key responsibilities include: architecting and implementing automated test frameworks for API, UI, and integration testing; designing robust test suites and integrating them into CI/CD pipelines; leading test strategy development and risk analysis for major features; proactively identifying systemic quality issues and driving cross-team process improvements; analyzing test coverage and implementing solutions to improve product quality; collaborating with engineering, product, and quality leaders on cross-functional initiatives; mentoring junior SDETs and QA team members; reviewing code and test cases for quality; maintaining test documentation and quality metrics; investigating and resolving complex defects through advanced debugging and root cause analysis; and advocating for quality best practices across engineering teams. Required qualifications: Bachelor's degree in Computer Science or equivalent experience; 5+ years in software development and test automation; advanced proficiency in multiple programming languages and test automation frameworks (Playwright, Cypress, Selenium, RestAssured); deep expertise in API, UI, and integration testing; proficiency in CI/CD pipeline integration; skilled in test strategy development and risk analysis; advanced debugging and troubleshooting; solid understanding of databases and SQL; experience with observability tools (DataDog, NewRelic); and excellent cross-functional communication and mentorship skills.

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