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Baldur's Gate 3 Script Extender
What it is
Baldur's Gate 3 Script Extender adds Lua and Osiris scripting support for Baldur's Gate 3 mods. A mod can turn on Lua through a feature flag and load bootstrap scripts for the client and server; the extender maintains separate Lua states for the server and each client. Its console can run Lua code and registered commands. Configuration includes debugger interfaces for Lua and Osiris, configurable listening ports, and file logging for Osiris activity, runtime output, story compilation, and compilation errors. An EnableAchievements option can re-enable achievements in modded games. SendCrashReports defaults to true and uploads minidumps after a crash. Installation involves extracting DWrite.dll into the game's bin directory, and the extender updates when the game launches. It supports Windows and Linux via Proton, but does not run on game versions older than patch 5; new releases target the latest game version. The tool is free to obtain under a license that includes MIT terms and a Commons Clause restriction on selling the software or substantially derived products and services. The license provides it as is and disclaims warranties.
For and against
For
- Adds Lua and Osiris support for mods
- Console runs Lua code and registered commands
- Includes debugger and file-logging configuration
- Can re-enable achievements for modded games
- Automatically updates when the game launches
Against
- Requires game patch 5 or later
- Releases target the latest game version
- Crash minidumps upload by default after a crash
- License restricts selling substantially derived products
The verdict
The extender provides scripting, debugging, and logging tools for Baldur's Gate 3 mods. Check game-version compatibility and the license conditions before using it.
Who it suits
This tool is for Baldur's Gate 3 mod creators who want to add Lua or Osiris scripting and use the available debugging and logging options.
Plans and prices
Baldur's Gate 3 Script Extender
Windows/Linux Proton modding tool · requires Baldur's Gate 3 · version-specific compatibility
Read 15 Oct 2026 · github.com
On the record
- Achievements
- The default configuration re-enables achievements for modded games.github.com · read 15 Oct 2026
- Automatic updates
- The updater downloads and applies the matching extender when the game launches, so GitHub releases represent updater changes rather than every extender build.github.com · read 15 Oct 2026
- Build requirements
- Developers are instructed to run first-time-setup.bat from an MSVC x64 Native Tools command prompt and then use Visual Studio.github.com · read 15 Oct 2026
- Client and server
- The extender maintains separate Lua states for the game server and each client.github.com · read 8 Oct 2026
- Console
- The extender provides an interactive console that executes Lua and can invoke Osiris functions.github.com · read 15 Oct 2026
- Console limitation
- The community installation guide says PlayStation and Xbox have no official Script Extender support.wiki.bg3.community · read 15 Oct 2026
- Crash reports
- The SendCrashReports option defaults to true and uploads minidumps to a crash report collection server after a game crash.github.com · read 8 Oct 2026
- Debugger ports
- The documented default ports are 9999 for Osiris debugging and 9998 for Lua debugging.github.com · read 15 Oct 2026
- Debugging
- Configuration supports console logging, runtime logs, compilation logs, an Osiris debugger and a Lua debugger.github.com · read 15 Oct 2026
- Documentation depth
- The Lua API document is about 1,957 lines and includes examples and function behavior details.github.com · read 15 Oct 2026
- Events API
- Lua scripts can subscribe to engine events with priority and one-shot options.github.com · read 15 Oct 2026
- Game data APIs
- Documented modules cover entities, stats, resources, localization, audio, templates, level operations and math.github.com · read 15 Oct 2026
- Game version limit
- The FAQ says the extender does not run on game versions older than patch 5 and new versions are released for the latest game version.github.com · read 8 Oct 2026
- Independent installation support
- BG3 Wiki says the extender can be installed manually or through Baldur's Gate 3 Mod Manager and updates itself at game startup.bg3.wiki · read 15 Oct 2026
- Independent praise: ecosystem importance
- A BG3 modding guide presents the extender as the foundation for writing mods with Lua and Osiris scripting.wiki.bg3.community · read 15 Oct 2026
- Independent praise: mod compatibility
- PC Gamer describes the extender as Patch 8 verified and often required for many other Baldur's Gate 3 mods.pcgamer.com · read 15 Oct 2026
- Installation
- The official release instructs users to extract DWrite.dll into the game's bin directory.github.com · read 15 Oct 2026
- Intended users
- The documentation describes using the extender in mods, including setting a mod configuration file and Lua feature flag.github.com · read 8 Oct 2026
