UE4SS
UE4SS is a free, open-source Windows toolkit for modding Unreal Engine 4 and 5 games.
What UE4SS is
UE4SS is a free, open-source Windows toolkit for modding Unreal Engine 4 and 5 games. It combines Lua scripting, a C++ modding API, blueprint mod loading, an SDK generator, a live property editor and dumping utilities. Documentation targets Unreal Engine versions 4.7 through 5.8. Lua and C++ APIs use the Unreal Engine object system, while blueprint mods can be spawned without editing or replacing game files. The Live Viewer searches, displays, edits and watches properties of loaded objects for runtime inspection and debugging. UE4SS can generate Unreal Header Tool-compatible headers, standard C++ headers from reflected classes and blueprints, .usmap mapping files and .umap files from loaded actors. Mods load through injection. Installation guidance includes basic and developer packages, experimental builds, manual injection and a central location for multiple games. The basic package is intended for users of dependent mods; the developer package adds tools for mod creators and debugging. UE4SS is not plug-and-play for every game, and some titles may require users to update AOBs themselves. Linux support is not expected soon.
Good
- Free and open source
- Lua and C++ mod APIs
- Blueprint mods without file replacement
- Live property inspection and editing
- Supports Unreal Engine 4.7–5.8
Watch out
- Windows 64-bit support only
- Not plug-and-play for every game
- Some games require AOB updates
- Lua documentation is incomplete
Who it suits
UE4SS suits Windows users who run or develop Unreal Engine mods and need scripting, blueprint loading, debugging or dumping tools. Developers should be comfortable with game-specific configuration.
Verdict
UE4SS provides a broad injection-based toolkit for Unreal Engine modding, from Lua scripts to runtime inspection and code generation. Its capabilities favor mod developers and technically minded users rather than universal one-click installation.
The facts
Each one read from UE4SS's own pages, with the date it was checked.
What it does
- Blueprint mods
- Blueprint mods can be spawned automatically without editing or replacing game files.checked 9 Oct 2026
- C++ mods
- UE4SS provides an API for writing C++ mods based on the Unreal Engine object system.checked 9 Oct 2026
- Code generation
- UE4SS can generate Unreal Header Tool compatible headers for a mirror project and standard C++ headers from reflected classes and blueprints.checked 4 Oct 2026
- Community support
- The documentation links to UE4SS and Unreal Engine modding Discord servers for community access.checked 9 Oct 2026
- Compatibility limit
- UE4SS is not intended to work plug-and-play with every game, and some games may require users to update AOBs themselves.checked 9 Oct 2026
- Compatibility limitation
- UE4SS is not described as a plug-and-play solution that works with every game; users may need to update AOBs themselves.checked 4 Oct 2026
- Config caveat
- Custom game configuration files may become outdated as games or UE4SS are updated, and the documentation directs users to report stale configs through the project repository.checked 9 Oct 2026
- Development requirements
- Building requires an MSVC version that supports C++23, Rust 1.73.0 or later, CMake 3.22 or later, and Ninja or MSVC as the build system.checked 9 Oct 2026
- Dumping tools
- UE4SS can generate Unreal Header Tool compatible headers, standard C++ headers with offsets, .usmap mapping files, and .umap files from loaded actors.checked 9 Oct 2026
- File and map utilities
- Its dumpers can generate .usmap mapping files for unversioned properties and dump loaded actors to generate .umaps in-editor.checked 4 Oct 2026
- Installation
- The basic installation uses a non-dev, non-experimental release extracted into the game's Binaries/Win64 directory; mod developers can use the zDEV version.checked 9 Oct 2026
- Installation options
- The installation guide describes basic and developer packages, experimental builds, manual injection, and a central install location for multiple games.checked 4 Oct 2026
- Intended users
- The basic install is intended for end users using UE4SS-dependent mods, while the developer install is intended for mod developers or users who need debugging, dumping, or other utilities.checked 4 Oct 2026
- Live property editor
- The live property viewer and editor can search, view, edit, and watch properties of loaded objects for mod debugging and runtime inspection.checked 9 Oct 2026
- Lua API status
- The Lua API page identifies itself as version 3.0.0 documentation and says its status is incomplete and its full overview may be out of date.checked 9 Oct 2026
- Lua mods
- Its Lua API lets users write mods based on the Unreal Engine object system.checked 9 Oct 2026
- Purpose
- UE4SS is a Lua scripting system, C++ modding API, SDK generator, Blueprint mod loader, live property editor, and set of dumping utilities for UE4/5 games.checked 9 Oct 2026
- Security reporting
- The project asks users to report sensitive security issues by emailing [email protected] rather than posting them to the issue tracker.checked 4 Oct 2026
- Support channels
- The documentation directs users to search existing issues and documentation first, then open an issue with context, platform versions, and logs when available.checked 4 Oct 2026
- Target versions
- The documentation describes targeting Unreal Engine versions 4.7 through 5.8.checked 9 Oct 2026
- UE support
- The documentation lists target Unreal Engine versions from 4.7 to 5.8.checked 4 Oct 2026
Where it runs
- Linux note
- The documentation says Linux support might happen eventually but not soon; it separately describes cross-compiling Windows binaries from Linux.checked 9 Oct 2026
- Platform
- The build documentation lists Win64 as its supported platform and says Linux support might happen later, but not soon.checked 4 Oct 2026
- Windows support
- The documented build platform is 64-bit Windows, and the build requirements call for a Windows computer.checked 9 Oct 2026
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