Why it matters

Transport choice determines what your MCP integration can do — local only, or remote, or over a load balancer. Understanding trade-offs is essential.

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The architecture

stdio: parent process spawns child; messages over stdin/stdout. Local only. Very fast.

SSE: HTTP GET for server → client stream; POST for client → server messages. Remote-capable.

MCP transportsstdiolocal, fastSSEremote, streamingStreamable HTTPmodern replacementStreamable HTTP replacing SSE as recommended remote transport
Transport options.
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How it works end to end

Streamable HTTP: single POST endpoint with SSE-style streaming response. Simpler than dual-channel SSE.

Auth: HTTP transports support OAuth, API keys. stdio inherits from parent process environment.

Firewalls: HTTP-based transports pass through more easily.