@bun-win32/psapi

Zero-dependency, zero-overhead Win32 PSAPI bindings for Bun on Windows.

Overview

@bun-win32/psapi exposes the psapi.dll exports using Bun's FFI. It provides a single class, Psapi, which lazily binds native symbols on first use. You can optionally preload a subset or all symbols up-front via Preload().

The bindings are strongly typed for a smooth DX in TypeScript.

Features

• Bun-first ergonomics on Windows 10/11.
• Direct FFI to psapi.dll (process enumeration, module info, memory stats, working sets, device drivers, and more).
• In-source docs in structs/Psapi.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (Psapi.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/Psapi.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/psapi

Quick Start

import Psapi from '@bun-win32/psapi';

// Optionally bind a subset up-front
Psapi.Preload(['EnumProcesses', 'GetModuleBaseNameW']);

// Enumerate all process IDs
const idBuffer = Buffer.alloc(4096);
const sizeNeeded = Buffer.alloc(4);

Psapi.EnumProcesses(idBuffer.ptr, idBuffer.byteLength, sizeNeeded.ptr);

const count = sizeNeeded.readUInt32LE(0) / 4;
console.log('Processes: %d', count);

[!NOTE] AI agents: see AI.md for the package binding contract and source-navigation guidance. It explains how to use the package without scanning the entire implementation.

Examples

Run the included examples:

bun run example              # Process enumeration + performance info

Notes

• Either rely on lazy binding or call Psapi.Preload().
• Windows only. Bun runtime required.
• SAL types & naming: nullability is in the type — Optional<T> (formally optional, SAL _*opt_) and Nullable<T> (plain [in]/[out] the docs say can be NULL), the null sentinel derived from T (null for pointers LP*/P*, 0n for handles/by-value addresses); direction is in the parameter name — _out (_Out_), _in_out (_Inout_), _In_ bare. See AI.md and the repo AGENTS.md.