Role Overview We are looking for a Senior JavaScript Engineer with a strong background in frontend technologies and a keen interest in application performance and user experience monitoring. This role focuses on building and enhancing our Real User Monitoring (RUM) solutions, which capture performance, errors, and user interactions across modern web applications. You will work on developing efficient, low-overhead JavaScript agents that run in the browser and provide deep visibility into how real users experience applications.
Responsibilities
- • Design and develop JavaScript-based monitoring agents that capture performance metrics, errors, and user interactions in the browser.
- • Work with browser performance APIs (Navigation Timing, Paint Timing, Long Tasks, Performance Observer) to track key metrics.
- • Implement support for Core Web Vitals (LCP, FID, CLS, INP) and other industry-standard KPIs
- . • Ensure that monitoring agents are lightweight, efficient, and non-intrusive.
- • Collaborate with backend/APM teams to correlate frontend traces with backend monitoring data.
- • Keep up with latest web performance standards and W3C specifications.
- Must-Have Skills • 3+ years of professional JavaScript/TypeScript development experience.
- • Strong expertise in browser APIs and event-driven programming.
- • Hands-on experience with performance measurement and optimization in web apps.
- • Solid understanding of Core Web Vitals and web performance monitoring.
- • Familiarity with cross-browser compatibility and web debugging tools.
- • Experience with one or more frontend frameworks (React, Angular, Vue).
- • Knowledge of compression techniques (gzip, brotli).
- • Exposure to RUM or frontend monitoring tools (New Relic, Datadog RUM, Dynatrace, Sentry, etc.). Nice-to-Have Skills
- • Experience building or contributing to JavaScript SDKs/agents
- . • Knowledge of Web Workers, Service Workers, WebSocket's.
- • Familiarity with Open Telemetry for frontend instrumentation.
- • Understanding of privacy and compliance in telemetry (PII masking, GDPR considerations).
- • Experience with session replay libraries and customization.
- • Prior contributions to observability, analytics, or APM solutions.
