Modernize a large fintech platform by building NestJS services and Next.js UIs, migrate transactional data to relational schemas, write comprehensive tests, identify and fix legacy problems, design scalable solutions that coexist with legacy systems, and use AI tooling responsibly to increase engineering velocity.

Perform manual exploratory testing and build/maintain automated test suites (Playwright/Selenium). Integrate tests into CI/CD, collaborate with product and engineering on acceptance criteria, investigate and track defects, and advocate shift-left testing and continuous quality improvements.