Transport and Security

Local Signer MCP is designed to keep signing local.

stdio

Use stdio for local tools and desktop clients.

Properties:

• no HTTP endpoint

• no TLS

• no network exposure

• best default for private keys

Docker

Use Docker when you want the same stdio entrypoint in a container.

Properties:

• still local-first

• useful for reproducible local setups

• pass secrets with --env-file LOCAL_SIGNER_ENV_FILE

• keep the env file on the host and do not commit it

• do not spell out private keys in the command line

streamable-http

Use streamable-http only when you need a URL-based connector.

Properties:

• HTTP transport exposed on a host and port

• optional TLS via certificate and private key files

• suitable for a trusted proxy or tunnel

If the client requires https://, use TLS termination. Keep the signer local unless you intentionally expose it through a trusted edge.

HTTP mode is unauthenticated. Bind it to 127.0.0.1 unless a trusted tunnel or reverse proxy controls access.

Node runtime

For GUI clients, prefer an absolute Node path instead of a bare node command.

After selecting the desired Node version, run which node and use that path in the client config.