Rojo is an open-source project management tool for Roblox developers, made by The Rojo Developers. Roblox Studio normally keeps a game's scripts and objects inside its own place file. Rojo lets developers keep them instead as ordinary files on the computer's filesystem, so they can use tools that work on files.
Rojo has a command-line program and a plugin for Roblox Studio. Developers write scripts in an external text editor such as Visual Studio Code, and Rojo syncs the files into Studio; models in the rbxm and rbxmx formats stream into the game in real time. An optional two-way sync in the Studio plugin writes supported Studio edits back to the files, and the rojo syncback command pulls objects from existing place files into a project. Because the project is a set of files, it can be versioned with Git (a version control system that records every change) and hosted on GitHub or GitLab. The command line can also package a project and deploy it to Roblox.
Rojo is free and open source under the Mozilla Public License 2.0.