Senior Software Development Engineer in Test (SDET)

Flex is a growth-stage, NYC headquartered FinTech company that is building the payment layer for life's essential bills, giving households one place to see, split, and pay their bills around how they live and get paid. By offering greater choice over how and when payments are made and allowing eligible on time payments to help build a positive credit history, Flex puts households back in control of their cash flow.
That work brings together people with different perspectives who challenge the status quo and take ownership of solving difficult problems. For you, that means doing the best work of your career next to people who make you better, and together bringing ideas to life that make a real impact for the people we serve.
About The Role
As a Senior SDET at Flex, you will own the test automation and quality efforts for entire product areas or major features. You will architect and optimize automation frameworks, lead test strategy for complex systems, and regularly collaborate across teams to deliver reliable and high-quality releases. This role offers the opportunity to mentor others, drive cross-functional quality improvements, and play a critical part in shaping the future of our engineering excellence.
What You’ll Do
Architect, implement, and optimize automated test frameworks for complex product areas, ensuring high reliability and maintainability
Design, develop, and maintain robust automated test suites for API, UI, and integration testing
Lead test strategy development and perform risk analysis for major features and systems
Integrate automated testing into CI/CD pipelines, supporting continuous integration and delivery processes
Proactively identify systemic quality issues and drive cross-team process improvements to increase coverage and efficiency
Analyze test coverage, identify gaps, and implement solutions to improve product quality
Collaborate closely with engineering, product, and quality leaders on cross-functional quality initiatives and release planning
Provide technical guidance and mentorship to junior SDETs and QA team members, fostering skill development and best practices
Review code and test cases contributed by other engineers for quality and maintainability
Maintain accurate and actionable test documentation, reports, and quality metrics for assigned product areas
Investigate and resolve complex defects and production issues through advanced debugging and root cause analysis
Advocate for quality and champion adoption of best practices within and across engineering teams
Proven ability to lead test strategy and risk analysis while making high-impact technical decisions amid ambiguity and prioritizing what matters most.
Key Qualifications
Bachelor’s degree in Computer Science or related field, or equivalent experience
5+ years of experience in software development and test automation
Advanced proficiency in multiple programming languages and test automation frameworks
Deep experience designing, building, and maintaining automation frameworks (e.g., Playwright, Cypress, Selenium, RestAssured)
Strong expertise in API, UI, and integration testing
Proficient in CI/CD pipeline integration and optimization
Skilled in test strategy development, risk analysis, and test architecture
Advanced debugging, troubleshooting, and root cause analysis
Solid understanding of database systems and advanced SQL
Experience with observability and monitoring tools (e.g., DataDog, NewRelic)
Excellent cross-functional communication and mentorship skills
Strong written and verbal communication skills; able to collaborate across functions
Compensation
Flex takes a market-based approach to pay, and compensation may vary depending on your primary work location. Work locations are categorized into one of three tiers based on a cost of labor index for that geographic area. The successful candidate’s starting pay will be commensurate with their experience, qualifications, and Flex’s internal leveling guidelines and benchmarks.
Tier 1 (NYC/Bay Area, Los Angeles, Seattle)
$136,000—$170,000 USD
Tier 2 (Austin, Washington D.C. Philadelphia, San Diego, Chicago, Atlanta)
$122,400—$153,000 USD
Tier 3 (Salt Lake City, all other USA cities)
$115,600—$144,500 USD
Life at Flex
We understand that it takes a diverse team of highly intelligent, curious, determined, empathetic, and self aware people to grow a successful company. Our HQ is located in New York City, but we have employees located throughout the US, Australia, Canada and South America. We are growing quickly, but deliberately, with a focus on building an inclusive culture. Our dynamic team has incredible perspectives to share, just as we know you do, and we take great pride in being an equal opportunity workplace.
Offices
Roles posted in New York, San Francisco, and Salt Lake City are hybrid positions with on-site expectations of 2-3 days per week in our local offices. For candidates outside of these areas, you may be eligible for our relocation assistance program.
Benefits
View our benefits and more at getflex.com/careers.

Work arrangement
Yes