Mohammed Mostafa

Worked as the sole Backend Engineer responsible for developing and maintaining the backend systems for Lesoll and EgyStay, managing production infrastructure, cloud services, and third-party integrations.

• Developed and maintained scalable REST APIs using Node.js, Express.js, TypeScript, and MongoDB.
• Built backend services for authentication, property management, bookings, payments, reporting, and admin operations.
• Implemented Redis caching and BullMQ background jobs to improve performance and reduce database load.
• Developed real-time features using Socket.IO, including chat, notifications, and online user tracking.
• Integrated Paymob and Amazon Payment Services, implementing secure payment workflows and webhook processing.
• Managed production infrastructure using AWS (EC2, S3, CloudFront, Route 53), Docker, Nginx, PM2, and GitHub Actions.
• Improved backend SEO by optimizing API performance and generating dynamic XML sitemaps for active listings.

• Built real-time collaborative diagram editing using Yjs CRDTs over a custom WebSocket server implementing the Yjs sync and awareness protocols, enabling live cursors, presence, and seamless multiplayer editing.
• Secured WebSocket connections with PASETO v4 authentication and enforced project-level role-based access control, while isolating collaboration sessions into dedicated board rooms.
• Designed a dual-snapshot persistence layer that stores both the authoritative Yjs binary state for lossless recovery and a denormalized JSON representation for efficient querying and API reads.
• Architected the backend using PostgreSQL/Prisma for relational data (users, projects, memberships, sharing) and MongoDB/Mongoose for high-frequency diagram mutations.
• Implemented horizontally scalable notifications using SSE with Redis Pub/Sub fan-out, alongside BullMQ workers for asynchronous email and notification processing.
• Improved platform reliability and security through Zod validation, Helmet, CORS, rate limiting, centralized error handling, structured logging with Pino, and Prometheus metrics. Verified collaboration behavior with integration tests and containerized the platform using Docker Compose behind Nginx.

• Built an open-source CLI tool that automatically generates index.ts barrel exports for large TypeScript codebases, reducing manual maintenance and import errors.
• Implemented recursive directory traversal with configurable exclusion rules, supporting scalable project structures and clean module organization.
• Designed the tool for developer productivity with automatic export generation, file watching, and seamless integration into existing Node.js/TypeScript workflows.
• Focused on Developer Experience (DX) by providing a lightweight, zero-runtime utility that integrates easily into existing development workflows.