Satisfactory Mod Loader

Satisfactory Mod Loader (SML) on Your Dedicated Server

SML is the foundation of the entire Satisfactory modding scene: the loader provides the hook through which mods are attached to the game and, at the same time, the compatibility API that practically every mod on ficsit.app builds on. Without SML no mod loads — it is not a content mod but the prerequisite for all the others. It is developed by the volunteer Satisfactory Modding organization (including Vilsol, Robb and mircearoata), which is not affiliated with Coffee Stain Studios but whose work the studio explicitly supports. The source code is published under GPL-3.0 on GitHub, and with close to one million downloads SML is the most installed building block in the scene.

Tip: Before every game update, write down the SML version your server last ran stably with — major game releases almost always require a new SML major line.

What differs on the server compared to the client

On the client, the Satisfactory Mod Manager handles installation. A dedicated server has no such convenience: SML and every mod live as separate folders under FactoryGame/Mods and must match the exact versions your players have installed. If even one mod version differs, the server refuses the join or silently skips loading the mod. Keep a list with the mod reference and version number per mod, share it with your group, and update server and clients in the same maintenance window.

The current SML 3.x line requires a minimum game version, which every mod carries in its metadata as game_version. After each game patch, first check whether SML itself received a new release, and only then the remaining mods — the dependency chain always runs from SML outward. After uploading, restart the server, watch the server log for errors while the mod folders load, and connect with a client that carries the same mods. Only when joining, saving and a second join after a restart all work should you open the server to your group.

Back up the save before every update: mods that add buildings or recipes leave entries in the save that are missing once the mod is removed and trigger warnings on load. A rollback to the last working combination of game version, SML and mods is then possible at any time without anyone having to rebuild the factory.