Deep proficiency in TypeScript, including advanced type system features Strong experience with React and modern frontend architectures Familiarity with browser internals (e.g., performance APIs, Web Vitals, event loop behavior) Experience building or maintaining client-side SDKs or instrumentation tools Strong advocate for testing, with experience using tools like Jest and Playwright/Cypress Comfort debugging and optimizing both applications and libraries Excellent verbal and written communication skills Experience using Git and modern CI/CD workflows Experience with OpenTelemetry or other observability frameworks Contributions to open-source projects in the JavaScript/TypeScript ecosystem Familiarity with browser privacy, data collection consent, and sampling strategies Experience designing developer APIs or libraries for long-term stability Experience with data visualization libraries like Recharts and D3 Interest in performance profiling, memory leak detection, and low-level browser behavior