TypeScript icon, indicating that this package has built-in type declarations

3.0.0 • Public • Published

arch ci npm downloads javascript style guide

Better os.arch() for node and the browser -- detect OS architecture

Sauce Test Status

This module is used by WebTorrent Desktop to determine if the user is on a 32-bit vs. 64-bit operating system to offer the right app installer.

In Node.js, the os.arch() method (and process.arch property) returns a string identifying the operating system CPU architecture for which the Node.js binary was compiled.

This is not the same as the operating system CPU architecture. For example, you can run Node.js 32-bit on a 64-bit OS. In that situation, os.arch() will return a misleading 'x86' (32-bit) value, instead of 'x64' (64-bit).

Use this package to get the actual operating system CPU architecture.

BONUS: This package works in the browser too.


npm install arch


var arch = require('arch')
console.log(arch()) // always returns 'x64' or 'x86'

In the browser, there is no spec that defines where this information lives, so we check all known locations including navigator.userAgent, navigator.platform, and navigator.cpuClass to make a best guess.

If there is no affirmative indication that the architecture is 64-bit, then 32-bit will be assumed. This makes this package perfect for determining what installer executable to offer to desktop app users. If there is ambiguity, then the user will get the 32-bit installer, which will work fine even for a user with a 64-bit OS.

For reference, x64 means 64-bit and x86 means 32-bit.

Here is some history behind these naming conventions:

Node.js proposal - os.sysarch()

Note: There is a proposal to add this functionality to Node.js as os.sysarch().


MIT. Copyright (c) Feross Aboukhadijeh.

Package Sidebar


npm i arch

Weekly Downloads






Unpacked Size

9.26 kB

Total Files


Last publish


  • feross
  • raynos