Modded Factorio is a different beast. You are not just launching a rocket anymore. You are building interstellar logistics networks in Space Exploration, wrestling with complex ore processing in Angel’s, or redesigning your entire factory around Krastorio 2’s tech tree. These playthroughs take weeks or months, and they are almost always more fun with friends.

But modded multiplayer has an extra layer of friction. The save file lives on the host’s machine, everyone needs matching mods, and if the host disappears for a week, your 200-hour modded world goes dark. SaveSync keeps that world accessible to your entire group.

The Modded Multiplayer Problem

Vanilla Factorio multiplayer already has the host-dependency issue: the world save exists only on the host’s machine. Modded Factorio makes this worse in two ways:

  • Mod version mismatches can prevent players from joining or corrupt saves
  • Modded playthroughs are longer so losing access to the save hurts more
  • Mod configurations are complex and manually transferring saves risks breaking things

When your group is 150 hours into a Space Exploration run and the host’s PC dies or they go on vacation, you do not want to be scrambling with manual file transfers and hoping nothing breaks.

How SaveSync Handles Modded Saves

SaveSync syncs your Factorio save file across every player in your group. The save file itself contains the mod configuration it was created with, so the game knows exactly what mods are required.

Here is the workflow for a modded group:

  1. Agree on a mod list with your group (use Factorio’s built-in mod portal or share a mod-list.json)
  2. Everyone installs the same mods and versions
  3. The host syncs the save through SaveSync after each session
  4. Any player pulls the latest save and hosts when they want to play
  5. The game validates mods on load so you will know immediately if something is mismatched

SaveSync handles the save file. Factorio handles the mod validation. Your group handles the factory design.

These are some of the most popular Factorio mod combinations that groups use in co-op:

  • Space Exploration - Extends the game with interplanetary logistics and exploration
  • Krastorio 2 - Overhauls progression with new resources, machines, and tech
  • Bob’s + Angel’s - Complete ore processing and production overhaul
  • Industrial Revolution 3 - Entirely new material progression system
  • Exotic Industries - New resources, planets, and production chains
  • Nullius - Chemistry-focused total conversion mod
  • Pyanodon’s - The most complex mod suite in Factorio

All of these create saves that are larger and more complex than vanilla. SaveSync handles them the same way because it works at the file level.

Setting Up SaveSync for Modded Factorio

  1. Install SaveSync from Steam.
  2. Create a sync group and add your friends via Steam.
  3. Coordinate your mod list so everyone is running the same mods and versions.
  4. Select Factorio in SaveSync and sync your save after each session.
  5. Any player can pull and host whenever they want to play.

If you run into any issues with modded saves, jump into our Discord server and the community can help you troubleshoot.

Tips for Smooth Modded Co-Op

  • Lock your mod versions before starting a long playthrough. Updating mods mid-save can cause issues.
  • Share your mod-list.json with the group so everyone can import the exact same configuration.
  • Sync after every session so the save is always up to date for the next player.
  • Communicate mod updates with your group before anyone updates. One player on a different mod version can block the whole group.

Your Modded Factory Deserves Better

You have invested hundreds of hours into your modded Factorio world. It should not be locked behind one player’s availability. With SaveSync, your entire group can keep the factory growing, no matter who hosted last.

Get SaveSync on Steam and join our Discord to connect with other modded Factorio players.