Frontend Engineer · Extramarks

Nov 2021 — May 2022

Owned the real-time UI layer for a live e-learning platform with thousands of concurrent classroom sessions. Built Socket.io-backed polling, Q&A, and session-sync features with optimistic UI. Led a strangler-fig refactor of 18,000 lines from class components to Hooks + useReducer — shipped without a single production regression.

Real-time classroom at scale — 18K lines refactored, zero regressions, latency <100ms.

Key Wins

• Teacher-to-student action latency: 2–4s → <100ms via optimistic updates + Redis pub/sub on the server side.
• Fixed 6 dangling EventEmitter listeners causing OOM crashes in sessions running over 45 minutes.
• 18,000-line React modernization (60+ components) shipped with no production regressions — verified by 400+ Jest snapshot tests.

See full portfolio: https://portfolio.kunal-gautam-570.workers.dev