The Transmission BitTorrent client does authenticated JSON-RPC; see “Remote Control” section of: https://trac.transmissionbt.com/wiki/ConfigurationParameters
E.g. setting.json file might look like: Code:{ “rpc-enabled”:1 “rpc-authentication-required”: 1, “rpc-password”: “xxxxxxxxxx”, “rpc-port”: 9091, “rpc-username”: “xxxxxxxxxx”, “rpc-whitelist-enabled”:1 “rpc-whitelist”:“127.0.0.1,192.168..” } It uses HTTP ‘basic’ authentication (Authorization: basic base64(username:password) in the HTTP headers).