Fallout 4 Script Extender (F4SE)

What Fallout 4 Script Extender (F4SE) is

Fallout 4 Script Extender (F4SE) is a free Windows resource for people creating mods for Fallout 4. It expands the game’s scripting capabilities without modifying the game’s executable files on disk. The listed plan costs nothing and supports Fallout 4 versions available on Steam and GOG.

F4SE’s documented interfaces include the Papyrus plugin API and hooks for Papyrus, Scaleform and the classic script system. The homepage lists build 0.7.9 for Fallout 4 runtime 1.11.240. Native code plugins for runtime 1.10.980 and later need to be updated by their creators, and F4SE’s API may change in later versions. Plugins must have publicly available source code.

The readme says Microsoft Store, Game Pass and Epic versions are unsupported. It explains that Windows Store applications do not allow the APIs required by script extenders. F4SE uses injection to load mods, which the readme says can trigger poorly written virus scanners; it says this is not evidence that f4se_loader is a virus. The project also lists Fallout 4 modding utilities, including a command-line BA2 archive extractor and a PEX script disassembler. The software is provided as-is. Installation and other problem reports go to the F4SE subreddit, while the team says it cannot help with load order problems.

Who it suits

F4SE is for Fallout 4 modders who need expanded scripting capabilities or are building plugins that use its documented interfaces. It suits players with a Steam or GOG version of the game who want to use mods that depend on the extender.

Limits

F4SE is free. Its stated storefront support covers Steam and GOG; Microsoft Store, Game Pass and Epic versions are unsupported. Native code plugins need updates from their creators for Fallout runtime 1.10.980 and later.

Getting started

1. Visit the F4SE website.
2. Confirm that your Fallout 4 version is from Steam or GOG and runs on Windows.
3. Check the homepage for the listed build and matching Fallout runtime.
4. Install F4SE for use with Fallout 4 mods that require it.
5. For help with installation or other problems, use the F4SE subreddit.

Verdict

Pick F4SE if you mod Fallout 4 on Windows using a Steam or GOG version and need expanded scripting support. Check plugin compatibility with your game runtime, since native code plugins need updates for later runtimes and the API may change. Players using MS Store, Game Pass or Epic versions cannot use it.