Job Description

#W2 Role

Job Title: Senior Frontend Engineer Real-Time Web Applications
Location: Malvern,PA

Job Description:
We are looking for a Senior Frontend Engineer with strong experience building production-quality JavaScript applications used in real-world environments. This role will focus on enhancing and scaling a Flask-backed, vanilla JavaScript dashboard that supports engineers during live production incidents.

The ideal candidate should have hands-on experience working on real-time web applications, especially in high-pressure operational environments. This position involves taking ownership of an existing dashboard, migrating it from polling-based updates to real-time push architecture, versioning APIs for broader external usage, and evolving the platform into a self-service solution for multiple teams.

This is a strong fit for someone who is highly effective with core JavaScript and browser fundamentals, without depending heavily on frontend frameworks. The current codebase is built in vanilla JavaScript, and that approach is expected to continue unless a very strong technical justification is presented.

Key Responsibilities:

• Own, maintain, and enhance a production dashboard built with vanilla JavaScript and Flask
• Migrate the application from polling-based updates to real-time push mechanisms such as WebSockets or Server-Sent Events (SSE)
• Design and support versioned frontend API integrations for external platform consumption
• Build scalable self-service capabilities for multiple internal teams
• Work across the full stack by reading, modifying, and extending Flask route handlers and Jinja2 templates
• Improve UI responsiveness and usability for engineers operating during active production incidents
• Profile and optimize frontend performance by identifying true bottlenecks and implementing targeted fixes
• Collaborate with backend and platform teams to improve API design, response handling, and system reliability

Required Skills:

• 8+ years of experience building production-grade frontend applications
• Strong proficiency in JavaScript, with deep understanding of DOM manipulation, event loop, fetch lifecycle, and browser rendering
• Proven experience building and supporting real-time web applications using WebSockets or SSE in production
• Strong knowledge of connection lifecycle management, reconnection handling, heartbeat mechanisms, and client-side state recovery
• Experience consuming or designing versioned APIs, including understanding breaking vs. non-breaking changes
• Ability to write API specifications before implementation and support version migrations from the consumer side
• Experience working on incident response, operations, or observability tools such as Datadog, Grafana, PagerDuty, Splunk, or similar platforms
• Hands-on experience with Flask and Jinja2 templates; able to work effectively in lightweight Python web environments
• Strong frontend performance tuning and profiling skills, including browser rendering analysis, network waterfall investigation, and API response optimization

Preferred Qualifications:

• Experience building dashboards or operational tools used during production incidents
• Familiarity with self-service platform development for multi-team usage
• Ability to work independently in an existing codebase and drive modernization efforts with minimal supervision.

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