A real-time collaborative code editor to solve a problem I kept running into myself — pair programming with friends remotely always meant fighting with screen-share lag or passing code back and forth over chat. DevCollab fixes that by letting multiple people edit the same file live, using Monaco Editor (the same editor that powers VS Code) paired with Socket.io for real-time synchronization, complete with live cursor tracking and role-based access control (owner/editor/viewer) so teams can control who can edit versus just view.Beyond live editing, I added peer-to-peer video and voice calling using WebRTC, so collaborators can talk while they code without switching to a separate app. On the backend, I implemented JWT-based authentication with bcrypt password hashing and refresh tokens for persistent, secure sessions, and designed a MongoDB schema to support versioned code history — so users can track changes and roll back to an earlier version if needed. I also integrated Razorpay for payments, with server-side signature verification to securely unlock premium features.The most interesting engineering challenge here wasn't broadcasting changes with Socket.io — it was thinking through session management, authorization logic for different user roles, and how to keep the editor feeling responsive while syncing state across multiple users in real time.