Valve barely touches the Steam client UI, so a small community of modders has been building the missing pieces around it. An XDA piece this month walked through the Millennium plugin loader as a starting point, and reading it made obvious how deep the Steam customization plugin ecosystem now goes. This is our short list of what to install after Steam itself.
Every pick below runs against the modern Steam client on Windows, most also work on Linux (including the Deck), and none of them require a modded Steam login.
What to look for in a Steam customization tool
- Whether it patches the client at runtime or edits files on disk (runtime patches survive updates more gracefully)
- Whether it ships with a plugin manager or expects you to edit CSS by hand
- Whether it touches the friends list, the library, or the store, since Valve rewrites each one at different cadences
- Whether it works on the Steam Deck’s SteamOS build, not only desktop Windows
- License and update cadence, because a dead loader breaks the moment Steam ships a client update
Quick comparison
| App | Best for | Platform | Cost | License |
|---|---|---|---|---|
| Millennium | Full theming and a plugin store | Windows, Linux | Free | Open source |
| SFP (Steam Friends Patcher) | Skinning the friends and chat window | Windows | Free | Open source |
| Steam Metadata Editor | Fixing wrong titles and images | Windows, macOS, Linux | Free | Open source |
| Steam Skin Manager | One-click swap between skins | Windows | Free | Open source |
| Decky Loader | Plugins for the Steam Deck UI | Linux (SteamOS) | Free | Open source |
| Steam ROM Manager | Adding non-Steam and emulator entries with art | Windows, macOS, Linux | Free | Open source |
| SteamGridDB Manager | Bulk custom artwork for your library | Windows, macOS, Linux | Free | Open source |
| Depressurizer | Autotagging and categorizing a large library | Windows | Free | Open source |
The apps
1. Millennium — best for full theming and a plugin store
Millennium is the closest thing Steam has to a real plugin ecosystem. It hooks into the running Steam client, exposes a plugin store called Steambrew, and hosts themes that restyle the entire UI (library, store, friends, downloads) rather than patching stylesheets one file at a time. Plugin authors ship in TypeScript and Python, so the catalogue grows quickly.
Where it falls short: Steam client updates occasionally break Millennium for a day or two while the maintainers push a patch. The Linux build is behind the Windows one.
Pricing:
- Free, open source under the MIT license.
Platforms: Windows, Linux.
Download: steambrew.app · GitHub
Bottom line: Install this first if you want Steam to look and feel like a modern app. Every other tool on this list plugs in cleaner once Millennium is running.
2. SFP (Steam Friends Patcher) — best for skinning the friends and chat window
SFP predates Millennium and targets one specific pain point: the friends and chat window resets its skin every time Valve rebuilds it. SFP re-patches the friends UI on start and on Steam update, so the skin actually persists. Community skins on the SteamFriendsPatcher subreddit range from a light Discord clone to old-Steam nostalgia builds.
Where it falls short: Only patches the friends window. Nothing in the library, store, or overlay.
Pricing:
- Free, open source.
Platforms: Windows.
Download: GitHub
Bottom line: The right tool if the chat window is the only thing you care about restyling and you do not want a full loader.
3. Steam Metadata Editor — best for fixing wrong titles and images
Steam Metadata Editor rewrites the launch options, sort names, hidden state, and artwork paths for every entry in the local library database. It is the fastest way to fix a game that shows up as “Untitled Goose Game (Origin)” or a shortcut with the wrong hero image, without having to right-click each entry inside Steam.
Where it falls short: No theming. Edits the database only, so a Steam reinstall wipes the changes unless you back up the shared_config.vdf.
Pricing:
- Free, open source.
Platforms: Windows, macOS, Linux.
Download: GitHub
Bottom line: Pair with SteamGridDB Manager for a full-artwork clean-up pass on a messy library.
4. Steam Skin Manager — best for one-click swap between skins
Steam Skin Manager is a small utility that keeps a folder of downloaded skins and switches between them without editing any Steam paths yourself. It handles the classic Metro for Steam skins, the newer library-focused packs, and dark themes for people who never liked the Steam 2019 refresh.
Where it falls short: Only manages classic skin files, not Millennium-era plugins. Windows only.
Pricing:
- Free, open source.
Platforms: Windows.
Download: GitHub
Bottom line: Use this if you want to keep three or four skins on hand and flip between them by mood.
5. Decky Loader — best for plugins on the Steam Deck
Decky Loader is the Millennium equivalent for the Steam Deck. It installs into SteamOS, adds a plugin browser inside the Deck’s overlay, and hosts plugins for TDP tweaking, per-game power profiles, CSS themes for Gaming Mode, and quick access to emulator front-ends. The plugin catalogue is the reason most Deck users flash it early.
Where it falls short: SteamOS updates from Valve can wipe it, so a reinstall after every major update is expected. Does not run on desktop Windows Steam.
Pricing:
- Free, open source.
Platforms: Linux (SteamOS).
Bottom line: If you own a Deck and you are not running Decky, you are missing the plugins that make the Deck feel like a Deck.
6. Steam ROM Manager — best for non-Steam and emulator entries with art
Steam ROM Manager scans folders of ROMs (or non-Steam launchers like Epic and GOG), generates shortcuts inside Steam, and pulls art from SteamGridDB so every entry looks native. Parsers exist for RetroArch, standalone emulators, and most desktop launchers, so a big-picture library can be built in one pass.
Where it falls short: The first-time setup takes an afternoon to configure parsers, and any change to your ROM folder means a re-parse.
Pricing:
- Free, open source.
Platforms: Windows, macOS, Linux.
Download: steamgriddb.com/manager · GitHub
Bottom line: The single best way to consolidate emulators and third-party launchers into Steam Big Picture without living inside another front-end.
7. SteamGridDB Manager — best for bulk custom artwork
SteamGridDB Manager replaces the game art (hero, grid, logo, icon) for entries in your Steam library from the SteamGridDB collection. Where Steam’s own right-click menu handles one asset at a time, this tool queues a full library in a single pass and pulls consistent art packs from community artists.
Where it falls short: Not a shortcut generator. Use Steam ROM Manager for adding entries, then this for polishing the art.
Pricing:
- Free, open source.
Platforms: Windows, macOS, Linux.
Download: steamgriddb.com/manager · GitHub
Bottom line: The finishing tool once your library structure is right and you want the shelf to look designed instead of random.
8. Depressurizer — best for autotagging a large library
Depressurizer reads a Steam library, pulls tags and genres from the store, and auto-generates categories so a 900-game backlog stops being one flat list. Rules are user-editable, so you can carve the library into buckets like “co-op only”, “under two hours”, or “left over from a bundle” and revisit them later.
Where it falls short: Interface looks like a WinForms utility from 2015 (because it is). Windows only.
Pricing:
- Free, open source.
Platforms: Windows.
Download: GitHub
Bottom line: The right tool for the day you finally sit down to organize a decade of Steam sale purchases.
How to pick the right one
If you want to change the way Steam looks: Millennium. It is the modern starting point and it hosts most of the interesting themes and plugins now.
If you only care about the friends window: SFP, because Millennium is overkill for a chat panel.
If your library has broken names or missing art: Steam Metadata Editor plus SteamGridDB Manager in the same afternoon.
If you own a Steam Deck: Decky Loader before anything else.
If you want emulators and non-Steam launchers to feel native: Steam ROM Manager, paired with SteamGridDB for art.
If your backlog is out of control: Depressurizer to break it into categories you will actually browse.
FAQ
Is Millennium safe to install?
Millennium runs entirely on the local machine and does not touch the Steam login flow, so a legitimate Steam account is not at risk of a VAC ban from installing it. It patches the client rendering layer, not any game process. Read the plugin sources before installing anything unfamiliar, same as with any browser extension.
Do these tools work on the Steam Deck?
Some do. Decky Loader is Deck-first. Steam Metadata Editor, Steam ROM Manager, and SteamGridDB Manager all work on Linux and therefore on desktop mode on the Deck. Millennium has a Linux build but the theme catalogue still targets Windows first.
Will a Steam client update break my plugins?
It can, and it does periodically. Millennium and Decky Loader both push updates within a day or two of Valve client changes. Old skin managers that patch specific CSS files break more often, which is why runtime loaders are the more resilient choice.
What is the best free way to theme Steam?
Millennium plus a theme from Steambrew is the shortest path. If all you want is dark mode for the friends window, SFP with a community skin does the job with less overhead.
Can I install these on macOS?
The Steam client on macOS lags the Windows one, so Millennium and Decky do not target it. Steam Metadata Editor, Steam ROM Manager, and SteamGridDB Manager work on macOS because they read the local library files rather than patching the client.
