.PEX File Extension

Papyrus is a scripting language Bethesda created for use in their The Elder Scrolls and Fallout series of video games. Papyrus scripts, which are typically written in PSC source code files and compiled to PEX binary files, are used to control in-game logic and trigger in-game events. Many Elder Scrolls and Fallout games contain Bethesda-developed PEX files.

Because Bethesda has given players access to the Papyrus scripting language, players who want to modify the PC versions of Skyrim and Fallout 4 can create their own Papyrus scripts and use them to customize the games' behavior. To do so, modders must:

1. Write and save their script as a source code file (usually a PSC file).
2. Use a Papyrus compiler to compile their script to a PEX file.
3. Place the PEX file in Skyrim or Fallout 4's data/​scripts folder.

If a modder wishes to modify the script an existing PEX file contains, they must first decompile the file to its editable, source code form.

You can use either Champollion (Windows) or PEXInspector (Windows) to decompile a PEX file to a PSC file. Then, you can open and edit the PSC file in any text or source code editor, such as Microsoft Visual Studio Code (cross-platform).

How do I compile a PSC file into a PEX file?

You can use the Papyrus Script Manager, which is included in the Bethesda Creation Kit, to compile a PSC file into a PEX file. Anyone who owns a PC copy of either Skyrim or Fallout 4 can download the Creation Kit from either Steam or the Bethesda.net Launcher.

To compile a PSC file to a PEX file:

1. Place your PSC file in your game's data/scripts/source folder.
2. Open the Creation Kit and select Gameplay → Papyrus Script Manager.
3. From the dropdown list that appears, select and right-click your PSC script.
4. Select Compile.

You can open PEX files with PopCap Games Peggle Extreme in Windows. To open a PEX file with the game, select REPLAYS from the main menu, choose the replay, and click PLAY. The PEX format is specific to Peggle Extreme, and it is incompatible with other Peggle versions or general video playback software.