Netiquette is a open-source tool used to monitor network connections via GUI as well as CLI for macOS
LuLu is a free open source firewall for macOS, capable of alerting and blocking unwanted connections.
TaskExplorer is a free open-source software enabling users to view running processes signatures, network connections, etc. on macOS.
Open-source storage browser supporting protocols/services including FTP, SFTP, WebDAV, Amazon S3, OpenStack Swift, Backblaze B2, Microsoft Azure & OneDrive, Google Drive and Dropbox.