Web & Mobile Task Scheduler

I need a small-footprint scheduling engine that runs in both a web application and its companion mobile app. The system will let end-users set up and manage: • meetings that push to their preferred calendar • one-off or repeating reminders with configurable notifications • fully recurring tasks (daily, weekly, custom) • WhatsApp messages dispatched automatically through the WhatsApp Business API Core expectations • A single codebase or tightly aligned services so web and mobile stay in sync in real time. • An intuitive UI for creating, editing, and canceling schedules. • Reliable background execution—think server-side cron or queue workers on the web side and native schedulers / push on iOS and Android. • Time-zone awareness, error logging, and basic analytics so I can monitor success or failure rates. • Clean documentation plus a quick start guide for deploying to staging and production. Acceptance will be based on: 1. Creating a task on one platform instantly visible on the other. 2. Correct firing of notifications and WhatsApp messages at the scheduled time, even after app restarts. 3. All code passing a short test suite and linting checks. I’m comfortable with mainstream stacks such as Node.js, Python, Firebase, or comparable solutions—use whatever lets you meet the above criteria efficiently.