SSE transport
The SSE transport is MCP's older remote transport: the server sends messages over an open Server-Sent Events stream, and the client posts to a second URL. Only 7 of the 727 servers linked from Claude listings still use SSE on October 13, 2026; 719 use Streamable HTTP.
- Servers still on it
- 7
- Out of
- 727
- In the spec
- Deprecated
More from our data
Our wider MCP dataset is the 425 open servers we track across every store, not only the 105 behind ChatGPT and Claude listings, with 7,777 tools. In it, 20 servers answer with an older protocol version than 2025-06-18.