Create a feature-rich chat application with a database (Firebase or MongoDB) for persistence and Socket.io for real-time messaging. Individual and group chats, message histories, typing indicators, read receipts, and user presence are among the features. Include image/file sharing, basic profile management, and authentication. Set up push alerts for web and mobile clients and deploy using PM2 or Docker.

Build an e-commerce platform's scalable RESTful backend with Express.js, MongoDB (Mongoose), and JWT-based authentication. Use the Stripe/PayPal sandbox to integrate the product catalog, categories, cart, order management, and payment gateway. Incorporate search/filter endpoints, pagination, input validation, and role-based access (admin/customer). Include logging, rate limiting, and simple unit tests.

Use WebSockets or Socket.io to create a bug-tracking system that provides real-time dashboard updates. Features include the ability to create, edit, and delete tickets as well as assign users, status workflow, comments, and attachments. Create an admin dashboard with filters and real-time metrics (open tickets, response time, assignments). Add CI/CD deployment using Docker and integrate webhook and email notifications.