ModSync is a SteamOS/Linux modding hub for Skyrim SE, including multi-device sync. Features include:
- Game version downgrading
- Thanks to Mulderland's Skyrim SE downgrader
- SKSE installation based on game version
- Mod Organizer 2 installer
- Thanks to MO2-LINT
- Multi-device sync for your Steam Deck, Steam Machine, Steam Frame, or other Linux hardware
Download the .flatpak from the releases tab.
SteamOS:
- Double click to open the
.flatpakfile in Discover and install it from there
Other:
flatpak install --user ~/Downloads/ModSync-*-x86_64.flatpak
flatpak run io.github.skjiisa.ModSyncTo build from source, see advanced.md.
It's recommended to close Steam for the first run
Home has buttons to install Mod Organizer 2 or use an existing installation. It offers the matching SKSE and any game-version repairs you need. Missing SKSE is optional: Play stays the primary action and the default controller choice. Choose "Guided setup" to go through MO2, game and SKSE, then optional sync. To bring a setup from another machine, choose "Copy setup from another machine…" on Home. That route pairs first and checks the required game version after the source's game-version record arrives, including if ModSync is reopened during sync.
"Steam launch" on Home shows whether the launch hook is on, off, pending or needs attention. It lets you add ModSync to Steam or have Steam's Play button open ModSync before Skyrim. These settings also remain available in Settings.
The Game version row on Home opens version management. Home also offers the available downgrade or "Keep this game version" action when Steam updates Skyrim. The management sheet includes restore, unpin and technical details.
ModSync allows syncing mod lists between multiple systems.
- Install ModSync on each system, set up Mod Organizer 2 on each, then choose one to be the host and pair the others using the "Sync with another machine" section.
- For easy pairing, have the host click "Pair over network", then on the other machine, press "Scan network" to have them find each other
- Enter the pairing code to confirm the connection
- You may need to allow ModSync through the firewall. If you see a warning, simply click "Allow in firewall..." to proceed.
Mod list syncing uses Syncthing under the hood
"Run in background" allows ModSync to run while closed so you don't have to worry about running it to keep your mods in sync between systems.
You can Launch Skyrim or Mod Organizer 2 through Proton with ModSync directly. If you want to have ModSync open when launching the game through Steam, click "Open ModSync before Skyrim", that way your mods can always stay in sync if you change them frequently.
- If using this setting, restart steam after enabling it
See advanced.md for command-line usage.
ModSync is free software under the GNU GPL, version 3 or later. See LICENSE. It builds on, bundles or downloads the components below. ModSync does not distribute any Bethesda game files. The downgrade patches are binary deltas that only apply to a copy of Skyrim Special Edition you already own through Steam.
| Component | Role | How you get it | License |
|---|---|---|---|
| Syncthing | sync engine, driven over its REST API | bundled in the Flatpak; otherwise downloaded from its GitHub releases on first use | MPL-2.0 |
7-Zip (7zz) |
unpacks the downgrade patch archives | bundled in the Flatpak, built from source; otherwise your system 7z, 7zz or bsdtar |
LGPL-2.1-or-later with the unRAR restriction and BSD-licensed parts, see its License.txt |
| SKSE | the Skyrim Script Extender | downloaded from skse.silverlock.org on request and verified against a pinned SHA-256; not bundled | its own license: free to redistribute unmodified, no source |
| xdelta3 | applies the binary patches | bundled in the Flatpak (3.1.0 from the xdelta-gpl repository); otherwise your system xdelta3 |
GPL-2.0-or-later |
| PySide6 / Qt 6 | the GUI | bundled in the Flatpak on the KDE runtime; a dependency of the source install | LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only |
| MO2-LINT | installs Mod Organizer 2 into the game's Proton prefix | downloaded on demand as a pinned prebuilt binary when you choose Install MO2 | GPL-3.0 |
| Mod Organizer 2 | the mod manager | installed by MO2-LINT; not bundled or downloaded by ModSync itself | GPL-3.0 |
| USVFS ARM64 backport | fixes MO2 2.5.2's process injection on ARM64 | downloaded on request, pinned and verified; source and build details | GPL-3.0 |
| Mulderland's Skyrim SE downgrader | the downgrade recipe and the community xdelta patches it points to | ModSync converts the recipe to JSON and downloads the patches from Mulderland's CDN only when you ask for a downgrade | no license declared upstream |
| httpx | HTTP client for the Syncthing API | Python dependency | BSD-3-Clause |
| platformdirs | data and config directories | Python dependency | MIT |
| qrcode | pairing QR codes | Python dependency | BSD-3-Clause |
| spake2 | PIN-authenticated LAN pairing, with cryptography |
Python dependency | MIT |
The Flatpak runs on the org.kde.Platform runtime, whose contents carry their own
licenses. Steam, Proton and protontricks are used where installed and are not part
of ModSync.