MCP Transports

MCP uses JSON-RPC 2.0 messages over two transport mechanisms. stdio for local servers running as subprocesses. Streamable HTTP for remote servers over HTTPS. The same protocol messages work over both.

Transports

stdio

since 2024-11-05

Local MCP servers running as child processes on the same machine as the client

+Zero network configuration – no ports, no TLS, no firewall rules

+Process isolation – server crashes do not affect the client network

+Works behind any firewall – pure local IPC

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Streamable HTTP

since 2025-03-26

Remote MCP servers accessible over the network, shared across multiple clients, deployed as services

+Remote access – server runs anywhere, clients connect over HTTPS

+Multiple clients – one server instance serves many clients simultaneously

+Standard HTTP infrastructure – works with load balancers, CDNs, API gateways

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