The Sims Mod Manager

A free, cross-platform desktop mod manager for The Sims 1, 2, 3 & 4 and The Sims Medieval.

Visit the website → · Follow on Tumblr

Browse, install, enable/disable, and clean up your mods and custom content for every mainline Sims game (and The Sims Medieval), in one app, with a UI that redraws itself to match the game you're managing.

One app, five interfaces

Switching games does more than re-tint: each one gets its own chrome, drawn after the game's own interface. The Sims 1's chiselled blue plates, the Sims 2's periwinkle lozenges lit in plumbob green, the Sims 3's blue glass, the Medieval's parchment and brass by day and carved wood after dark, and the Sims 4's flat mint. Every one of them comes in light and dark, following your system or your own pick in Settings.

Light	Dark

Features

• Per-game themed UI: the whole app re-skins as you switch between The Sims 1, 2, 3, 4 and Medieval - colors, logos and the shape of every button - complete with the classic Sims 1 UI sounds, in light or dark.
• Real thumbnails & insights: .package files are parsed (DBPF) to pull out embedded artwork and a content breakdown (CAS parts, textures, tuning...), so your library looks like a library, not a file list.
• Library with search, category filters (Package/Script/Object/...), grid and list layouts, sorting by name, date or size (with the option to keep disabled mods at the bottom), and live Total/Enabled/Disabled/Conflicts stats.
• One-click enable/disable: disabling renames the file with a .disabled suffix so the game's loader skips it; nothing is ever deleted. You can pick the suffix yourself to match another manager, and mods something else disabled (CC Magic's .off) show up in the library too.
• Conflict warnings: enabled mods are badged when they share a file name, when two versions of the same mod are installed side by side, and when their packages actually share DBPF resource keys (the real thing: the game keeps whichever copy it loads last).
• Finds your folders for you: localized user folders ("Los Sims 3", "Die Sims 2", the Ultimate Collection), every install when a game exists more than once, and you can point at any folder manually.
• Mods-folder scaffolding: if a game has no mods folder yet, the app creates it with the files the game needs (e.g. the Sims 3 Resource.cfg framework).
• Install: pick mod files (filtered to the game's real extensions) or drop files and folders straight onto the window; .zip, .rar and .7z archives are unpacked for you, keeping their folder structure and skipping readmes and screenshots.
• The Exchange: a mod shop inside the app. Browse the whole catalog, filter by game, install in one click, and get an Update button when a creator ships a new version of something you already have.
• Saves: read-only insight into your save files - households, funds, photo albums, and world stats like population, net worth, life stages and top skills, without opening the game.
• Packs: every expansion, game pack, stuff pack and kit installed next to the game, with its artwork and its size on disk. The Sims 4 and The Sims 3 can be switched off from here without moving a single file; nothing is ever uninstalled.

_{A mod's detail view: what's inside the package, where the file lives, and why it got flagged.}

The Exchange

The app has its own mod shop, currently in alpha. Publishing is free at the creator portal, and what you publish shows up on everyone's shelves.

_{The shelves, filtered by game. Installing puts the file in the folder of the game the listing names, whichever game you're currently looking at.}

_{A listing brings its screenshots and install notes along, and turns into an Update button once the creator publishes a newer version.}

Saves

Read-only insight into your save files, no game launch required: every household with its funds and members, a photo album, and world stats (population, net worth, life stages, top skills). Support varies per game by what each save format actually holds.

_{Every save's households, backups included. Open one to see its funds, its house, and who's living there.}

_{World stats for the whole save: population, net worth, life stages, even the highest skill in the save.}

Packs

The publisher's own content, listed beside your mods: expansions, game packs, stuff packs and kits, each with its artwork, its code and what it takes up on disk. Where a game has a safe way to run without one, there's a switch. The Sims 4 writes the same packstoskipmount line its own Pack Selection screen uses; The Sims 3 takes the pack out of the registry the launcher reads (Windows, administrator rights); the Sims 2 switches sit behind an experimental opt-in in Settings, because a neighborhood played with a pack can break when it's opened without one. The Sims 1 merged its expansions into the base game, so there the screen is a list. Either way nothing is moved or uninstalled, and the game picks the change up on its next start.

_{A pack you switch off stays installed; the game just stops loading it. Useful for a lighter game, or for finding out which pack a mod is really fighting with.}

Download

Grab the latest version from the Releases page. Free, no account needed.

Platform	File	Notes
Windows (installer)	TheSimsModManager-x.y.z-windows-setup.exe	Recommended. SmartScreen may warn (app isn't code-signed yet); choose More info → Run anyway
Windows (portable)	TheSimsModManager-x.y.z-windows-portable.zip	Extract anywhere, run sims_mod_manager.exe
macOS	TheSimsModManager-x.y.z-macos.dmg	Signed & notarized by Apple. Open it and drag the app into Applications
Linux	TheSimsModManager-x.y.z-linux-x64.tar.gz	Extract, run sims_mod_manager

Supported games

Game	Default mods location	Notes
The Sims	<install>\The Sims\Downloads	Lives in the install folder, not Documents
The Sims 2	Documents\EA Games\The Sims 2\Downloads	Ultimate Collection uses its own folder name
The Sims 3	Documents\Electronic Arts\The Sims 3\Mods\Packages	Needs the Resource.cfg framework; the app creates it for you
The Sims Medieval	<install>\The Sims Medieval\Mods\Packages	Lives in the install folder (Documents only holds saves); needs a Resource.cfg in the install root - the app creates it for you
The Sims 4	Documents\Electronic Arts\The Sims 4\Mods	Created by the game on first launch; enable CC/script mods in game options

All of these are best-effort defaults: every game's folder can be overridden in Settings, which covers custom drives, localized folder names, OneDrive-relocated Documents, and Wine/CrossOver prefixes on macOS/Linux.

The core is game-agnostic by design: support for the SimCity series (and any other moddable game) can be added without touching the rest of the app. See docs/adding-a-game.md.

Building from source

Requires the Flutter SDK with desktop support enabled.

flutter pub get
flutter run -d windows   # or: -d macos / -d linux

Run the tests and analyzer with flutter test and flutter analyze. More detail in docs/architecture.md.

Languages

The app and the website speak eleven languages. English and Portuguese are mine; the other nine were done by simmers who actually play in them, which is why they use each scene's own modding slang instead of a dictionary translation:

Language	Translated by
English	rodrifelix99
简体中文	xiaoyu_sims
Español	marisol_plumbob
Português (Brasil)	rodrifelix99
Français	clodesims
Deutsch	plumbobjonas
Italiano	giuliapixel89
Русский	verasimka
Polski	kasia_pxl
日本語	mochi_simjp
Ελληνικά	friendofbellas

Spotted something that reads wrong in your language, or want to add one that isn't here? The strings live in lib/l10n (app) and web/src/i18n (website) - open an issue or a PR, credit included.

Contributing

Bug reports, feature ideas, and pull requests are very welcome; see CONTRIBUTING.md. Good first stops:

• The Wiki: user guide & FAQ
• The Tumblr blog: news & release announcements
• docs/architecture.md: how the app is put together
• docs/adding-a-game.md: add support for a new game

Thanks

A good chunk of this app exists because someone with more patience than me answered a question at a bad hour:

• bunsenpixel, who figured out that a macOS window keeps the material it was born with, so the blur has to be set inside waitUntilReadyToShow and not a frame later. Two evenings of staring at a solid white window, fixed in one message.
• wanderbyte, for spotting that bsdtar unpacks .rar/.7z through \\?\ paths and then leaves behind names the normal Windows API can't reach again, which is why a single deep archive was taking whole installs down with it.
• mothcache, for the RefPack notes that got the DBPF parser reading compressed resources instead of shrugging at half the packages in my Mods folder.
• plumbtreemods, who knows exactly where every kind of Sims 1 file is meant to land, mesh-name prefixes for buyable clothing included. The Sims 1 routing rules are theirs, I only wrote them down in Dart.
• hexley_j, for the Inno Setup warning that stopped me changing the AppId and shipping an "upgrade" that installs itself a second time next to the old one.

And to everyone who reported a bug with a screenshot and their real folder layout attached: that saves more time than it looks like it does.

Where AI fits in

Claude turns up in this repo's contributor list now and then. It writes comments, docstrings, and paragraphs like this one - the spots where "correct and clear" is the whole job since English and clear documentation is not native to me. It has never touched the DBPF parser, the sims3pack offset math, or the conflict detector; those are mine, line by line, and I can walk you through any of them if you ask. I don't merge code I can't explain myself, full stop. Longer version, with the two bugs that taught me why that matters: Say no to vibe coding.

Roadmap

SimCity support · more games via the adapter system. See the open issues for what's planned and to suggest more.

License & disclaimer

The source is available for reading and contributing, but this is not an open-source license: the code may not be reused or redistributed. The app itself is free to download and use. See LICENSE.md.

The Sims Mod Manager is an unofficial fan project. It is not affiliated with, endorsed by, or sponsored by Electronic Arts Inc. or Maxis. The Sims, SimCity, and all related logos, artwork, and sounds are trademarks or copyrighted material of Electronic Arts Inc. and are used here for identification and interoperability only.