REST over HTTP request-response is ideal for resource operations and ordinary application workflows.

Server-Sent Events (SSE) provide a one-way stream from server to client and are useful for notifications and live updates.

WebSockets provide bidirectional communication and are useful for interactive real-time systems such as chat, multiplayer applications, and collaborative editing.

These technologies are not competitors in every situation. A production application can use REST for CRUD operations, WebSockets for live collaboration, and webhooks for external integrations.