Extensions can communicate with a native helper app actually. This looks like an FTP capable extension. https://chrome.google.com/webstore/detail/sftp-client/j

Extensions can communicate with a native helper app actually. This looks like an FTP capable extension. https://chrome.google.com/webstore/detail/sftp-client/jajcoljhdglkjpfefjkgiohbhnkkmipm?hl=en-GB https://chrome.google.com/webstore/detail/sftp-client/jajcol... Not sure if it uses a proprietary proxy though.