Debloat Guide

Three scripts in devops\, driven by a single config.txt, remove engine content you do not need. Everything defaults to dry run and move rather than delete, so a mistake is recoverable.

A full Unreal Engine 4.27 source tree contains support for every platform, every workflow and every template Epic ships. A Win64-only project uses a fraction of it. Debloating recovers disk space and reduces build time.

Original Vite debloat scripts by Bikouz.

The suite

All three live in devops\ at the engine root and read devops\config.txt. You can pass an alternative config path as the first argument.

Safety model

The scripts are deliberately conservative, and it is worth understanding how before running them.

Dry run is the default. DRYRUN=1 prints every action without touching a file. Review the output before changing it.

Move is the default, not delete. MODE=move relocates targeted files into MOVE_DIR, preserving their relative layout so they can be restored by copying back. MODE=delete is permanent.

The move destination cannot be inside the engine tree. The script refuses, because a move destination inside the tree would be caught by subsequent passes.

Drive roots are refused. Both the engine root and the move destination are checked.

The engine root is validated. The script confirms Engine\Binaries\ exists before doing anything.

Configuration

devops\config.txt uses KEY=VALUE lines. Comment a line out with # to preserve what it targets; uncomment to enable an optional target. This inversion is worth internalising: an uncommented STRIP line means that thing gets removed.

Core settings

MODE=move
MOVE_DIR=..\ViteDebloat_Moved
DRYRUN=1

MOVE_DIR resolves against the engine root, so the default is a sibling folder of the engine.

Platforms

Win64 is always kept. Uncomment a platform to also download and keep its dependencies during SetupSlim:

#KEEP_PLATFORM=Android
#KEEP_PLATFORM=IOS
#KEEP_PLATFORM=Linux
#KEEP_PLATFORM=Mac
#KEEP_PLATFORM=HTML5

Do this before running setup. Not downloading a dependency is cheaper than downloading and then deleting it.

Templates

STRIP_OTHER_TEMPLATES=1
KEEP_TEMPLATE=TP_ThirdPerson
KEEP_TEMPLATE=TP_ThirdPersonBP
KEEP_TEMPLATE=TemplateResources

Every folder under Templates\ not named by a KEEP_TEMPLATE line is targeted. TemplateResources is shared by all templates and must be kept if you keep any template.

Strip targets

The default target list, grouped by category:

Platform binaries not needed for Win64

STRIP=Engine\Binaries\Win64\Android
STRIP=Engine\Binaries\Win64\IOS
STRIP=Engine\Binaries\Win64\Lumin
STRIP=Engine\Binaries\DotNET\IOS

Non-Windows deployment and development tools

STRIP=Engine\Extras\Android
STRIP=Engine\Extras\iTunes
STRIP=Engine\Extras\Xcode
STRIP=Engine\Extras\Instruments
STRIP=Engine\Extras\GDBPrinters
STRIP=Engine\Extras\LLDBDataFormatters
STRIP=Engine\Extras\Maya_AnimationRiggingTools
STRIP=Engine\Extras\MayaVelocityGridExporter

3ds Max scripts are preserved by default, since 3ds Max is a Windows DCC tool.

UnrealFileServer

STRIP=Engine\Binaries\Win64\UnrealFileServer.exe
#STRIP=Engine\Source\Programs\UnrealFileServer

UnrealFileServer serves cooked and staged files to remote devices and powers network Cook-on-the-Fly. It is safe to remove if you develop and package only for local Win64, do not deploy to remote devices, do not use network Cook-on-the-Fly, and do not target consoles or mobile through the file-server workflow.

The prebuilt binary is targeted by default; the source folder is preserved so the tool can be rebuilt later.

Engine content

STRIP=Samples\StarterContent
STRIP=Samples\MobileStarterContent
STRIP=FeaturePacks\StarterContent.upack
#STRIP=Samples\NGXTest
#STRIP=Samples\PixelStreaming
#STRIP=Samples\RTXGI_Test

Starter Content is removed per the debloat policy. The fork-specific test samples are preserved by default — RTXGI_Test in particular is useful when verifying DDGI.

Entries that do not exist in the tree are skipped with a notice, which is harmless.

The plugin pass

Disabled by default, because plugin needs vary per project:

#PLUGIN_LIST=ExcludedPlugins.txt

ExcludedPlugins.txt lists roughly 200 engine plugin paths, covering mobile and XR platforms, source control providers other than the one you use, Chaos plugins (unnecessary since Vite uses PhysX), enterprise and virtual production tooling, and a large set of experimental plugins.

The file is looked up next to the scripts first, then in the engine root.

Read ExcludedPlugins.txt before enabling this pass. It includes entries your project may need — Engine/Plugins/Runtime/GameplayAbilities/, Engine/Plugins/Runtime/ApexDestruction/, Engine/Plugins/Runtime/HairStrands/, Engine/Plugins/Runtime/Nvidia/ (which contains the DLSS and Streamline plugins) and Engine/Plugins/Runtime/PhysXVehicles/ are all on the list.

Comment out the lines for anything you use before running the pass.

Running it

Open devops\config.txt and review every uncommented STRIP line. Comment out anything you need. Confirm DRYRUN=1 and MODE=move. Run ueVite-debloat-StripExecute.bat and read the full output. This is the step people skip and then regret. Set DRYRUN=0 and run it again. Build the engine and open the editor. Confirm your projects still load and the plugins you need are present. Once you are confident, delete MOVE_DIR to actually reclaim the space. Until you do, the files are still on disk.

For a fresh clone, run ueVite-debloat-SetupSlim.bat instead of Setup.bat so unneeded platform dependencies are never downloaded in the first place.

Debug symbols

ueVite-debloat-StripDebugSymbols.bat removes PDB files according to ExcludedPdbs.txt. Debug symbols are a large fraction of a source build's disk footprint.

Keep symbols for anything you might need to debug. Stripping symbols for the engine modules you never step into is a large saving; stripping symbols for the ones you do turns a readable callstack into hexadecimal.

Restoring

In move mode, MOVE_DIR mirrors the engine tree's relative layout. Copy the contents back over the engine root to restore.

If you used delete mode, restoration means re-cloning or re-running Setup.bat.

What this does not do

Debloating reduces disk footprint and, through the plugin pass, build time. It does not improve runtime performance — a plugin that is present but disabled costs nothing at runtime.

For runtime performance, see Profiling and Engine Default Changes. For build time specifically, removing the added Vite plugins saves roughly three minutes on a full 15-minute build; see Shader Compilation and PSO.

See also

• Build from Source
• Engine Default Changes
• Bundled Plugins
• Cache Management