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WebSockets vs Server-Sent Events (SSE)



  • Definition: A protocol providing full-duplex communication channels over a single TCP connection.
  • Usage: Often used for real-time applications like chat systems, live feeds, and interactive games.

Server-Sent Events (SSE)

  • Definition: A server push technology enabling a browser to receive automatic updates from a server via HTTP connection.
  • Usage: Suited for unidirectional data flow such as notifications, stock price updates, and news feeds.
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Key Comparisons

  1. Communication Type

    • WebSockets: Bi-directional; both client and server can initiate communication.
    • SSE: Unidirectional; only the server sends data to the client.
  2. Protocol

    • WebSockets: Uses its own protocol (ws:// or wss:// for secure connections).
    • SSE: Operates over standard HTTP/HTTPS protocols.
  3. Connection Handling

    • WebSockets: Maintains a persistent connection, requiring a dedicated server.
    • SSE: Uses an HTTP connection, benefiting from existing web infrastructure and proxies.
  4. Complexity and Overhead

    • WebSockets: More complex to implement and maintain; higher overhead due to control frames.
    • SSE: Simpler to implement, especially on the server side; lower overhead.
  5. Browser Support

    • WebSockets: Broadly supported in modern browsers.
    • SSE: Limited support in Internet Explorer and older browsers.
  6. Use Cases

    • WebSockets: Ideal for applications requiring two-way communication like live chats and online gaming.
    • SSE: Better suited for updating clients with real-time information where client-to-server communication is not required.
  7. Scalability

    • WebSockets: Can be challenging to scale due to persistent connections.
    • SSE: More scalable in scenarios where the client doesn't need to send data to the server.


  • Choose WebSockets: When you need a robust, real-time, two-way communication between client and server.
  • Choose SSE: For simpler, one-way communication scenarios, particularly when updates are predominantly from server to client.