Gobby is a collaborative, multi-user text editor that allows multiple users to simultaneously edit a document over the internet. Sessions can be password protected to control which users are allowed access to a set of documents. Gobby also includes an Access Control List system that can be used to provide fine-grained control over which users can edit what documents. For security, all data transferred over the internet is encrypted using ciphers that provide perfect forward secrecy. Syntax highlighting for most popular languages is provided by the GtkSourceView library, which supports programming languages (C/C++, Java, Fortran, etc), scripting languages (Python, Perl, PHP, etc), and markup languages (XML, HTML, Markdown, etc). Gobby also features an in-session group chat and per-user undo that doesn't remove changes made by other users. Windows executables are available via the Gobby website. Most Linux distributions include Gobby in their package managers. MacOS users can install Gobby via MacPorts, homebrew, or nixpkgs. Gobby is free software, distributed under the ISC license, with source code available on GitHub.