bun-win32

Zero-dependency Win32 FFI bindings for Bun on Windows. Each system DLL is a standalone @bun-win32/* package with full type definitions.

Install

# Per-DLL packages:
bun add @bun-win32/kernel32 @bun-win32/user32 # etc...

# Or pull the entire surface in one install:
bun add @bun-win32/all     # scoped meta-package
bun add bun-win32          # unscoped alias for the same surface

Requires Bun >= 1.1.0 and Windows 10+.

Usage

After the first call resolves the symbol via dlopen/dlsym, the native function pointer is cached directly on the class. Every subsequent call is a straight pointer invocation through Bun's FFI - no marshaling layer, no runtime type checks, no wrapper overhead. It's the same codepath as calling the C function yourself.

For hot paths, Preload() resolves symbols eagerly so even the first call pays zero binding cost:

import Kernel32 from '@bun-win32/kernel32';

const pid = Kernel32.GetCurrentProcessId();
const ticks = Kernel32.GetTickCount64();

import User32 from '@bun-win32/user32';

User32.Preload(['GetForegroundWindow', 'SetWindowPos']);

const { GetForegroundWindow, SetWindowPos } = User32;

SetWindowPos(hWnd, 0n, x, y, width, height, flags);

[!IMPORTANT] If you destructure before binding, you capture the lazy wrapper instead of the native function.

Packages

All type definitions are provided by @bun-win32/core.

Published packages are AI-friendly. Alongside the README.md, each package includes an AI.md file that documents the binding contract, type surface, and source layout so coding agents can use the package correctly.

Graphics & Windowing

• comctl32 - common controls, image lists, property sheets, DPA/DSA dynamic arrays, flat scroll bars, window subclassing
• comdlg32 - common dialogs: Open / Save File, Choose Color, Choose Font, Print, Page Setup, Find / Replace, and CommDlgExtendedError
• d2d1 - Direct2D: GPU-accelerated 2D — ID2D1Factory / device-context creation plus Direct2D's native affine-matrix, color-space (sRGB / scRGB), gradient-mesh (Coons-patch), and trig / vector math (D2D1CreateFactory, D2D1MakeRotateMatrix, D2D1ConvertColorSpace, …)
• d3d11 - Direct3D 11 device / swap-chain creation, D3D11-on-12 interop, WinRT IDirect3DDevice / IDirect3DSurface bridges
• d3d12 - Direct3D 12 device creation, debug-layer / global-interface access, and root-signature serialize/deserialize (D3D12CreateDevice, D3D12GetDebugInterface, D3D12GetInterface, D3D12SerializeVersionedRootSignature, …) — modern GPU/compute/ML path
• d3dcompiler_47 - HLSL → DXBC shader compilation, preprocessing, disassembly, reflection, blob part extraction, shader stripping, function linking graph
• dcomp - DirectComposition device/surface creation (DCompositionCreateDevice/2/3, DCompositionCreateSurfaceHandle) and the Windows-11 compositor-clock frame/statistics surface (DCompositionGetFrameId, DCompositionGetStatistics, DCompositionWaitForCompositorClock, DCompositionBoostCompositorClock) — live compositor heartbeat proven pure-FFI
• dwmapi - DWM composition, blur, thumbnails
• dwrite - DirectWrite factory entry point (DWriteCreateFactory): system font enumeration, text layout, glyph metrics, and pure-FFI ClearType/grayscale glyph rasterization over the IDWriteFactory COM vtable
• dxcore - DXCore adapter-factory entry point (DXCoreCreateAdapterFactory): DXGI-independent GPU & compute-only MCDM adapter enumeration, hardware IDs, memory pools, and capability/attribute queries over the IDXCoreAdapterFactory/List/Adapter COM vtable
• dxgi - DXGI adapter enumeration, factory creation, debug interface (`CreateDXGIFact

... View full README on GitHub