• Architecture & Scale: Rebuilt the backend (v3) as sole owner, reducing Firebase reads from 1M/day to 40K/day (96%) via query, route, and JSON-response optimization plus RTDB caching cutting infrastructure cost and removing read-quota risk as the user base scaled past 150K.
• Payments: Designed and shipped end-to-end subscription billing on Razorpay and RevenueCat, resolving international recurring-payment failures and unblocking global revenue collection.
• Feature Ownership: Shipped a Content Writer Dashboard for safe production publishing and a real-time Share Notes system (granular permissions, invites, live sync).
• Systems & AI: Built a backend push-notification engine (message queues, fan-out, FCM) for campaign delivery; led R&D on speech-to-text migration via Azure fine-tuning and on-device Whisper.
• Compliance & Security: Implemented GDPR/HIPAA-aligned data handling and scoped SSL pinning/TLS 1.3 to mitigate MITM risk, clearing the product for regulated markets.
