FEToolkit/User-Agent

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FEToolkit User-Agent is a utility library that accurately parses and analyzes browser User-Agent information. It prioritizes the User-Agent Client Hints API and falls back to parsing traditional User-Agent strings for browsers that don't support it.

1. Compatibility

| Browser | enabled | | :-----------------------------------------: | :-----: | | chromium based browsers | | | Google Chrome | ✅ | | Naver Whale | ✅ | | Opera | ✅ | | MicroSoft Edge | ✅ | | OpenAI Atlas | ✅ | | Samsung Internet | ✅ | | webkit based browsers | | | Safari | ✅ | | etc | | | Firefox | ✅ |

2. Getting Started

2-1. Installation

• npm

  npm i @fetoolkit/user-agent

• yarn

  yarn add @fetoolkit/user-agent

• pnpm

  pnpm add @fetoolkit/user-agent

3. Usage

getUserAgent

Retrieves the current browser's User-Agent information. Provides more accurate information when User-Agent Client Hints API is supported, and falls back to parsing traditional User-Agent strings when not supported.

import { getUserAgent } from '@fetoolkit/user-agent';

// Use as an async function
const agentInfo = await getUserAgent();

console.log(agentInfo);
// Example output:
// {
//   browser: {
//     name: 'chrome',
//     version: '120.0.0.0',
//     majorVersion: 120,
//     webkit: false,
//     webkitVersion: '-1',
//     chromium: true,
//     chromiumVersion: '120.0.6099.109',
//     webview: false,
//     isEdgeBrowser: false,
//     jsEngine: 'v8
//   },
//   os: {
//     name: 'window',
//     version: '10.0.0',
//     majorVersion: 10
//   },
//   isMobile: false
// }

Notice

• in OpenAI Atlas, browser name will be return as 'chrome'(Nov 2025)
  • Atlas's own UA Brand Information is not registered yet.

Return Data Structure

AgentInfo

interface AgentInfo {
  browser: AgentBrowserInfo;
  os: AgentOSInfo;
  isMobile: boolean;
}

AgentBrowserInfo

interface AgentBrowserInfo {
  name: string; // Browser name (chrome, firefox, safari, etc.)
  version: string; // Browser version
  majorVersion: number; // Major version number
  webkit: boolean; // Whether it's a WebKit-based browser
  webkitVersion: string; // WebKit version
  chromium: boolean; // Whether it's a Chromium-based browser
  chromiumVersion: string; // Chromium version
  webview: boolean; // Whether it's a WebView environment
  isEdgeBrowser: boolean; // Whether it's Edge browser
  jsEngine: JavaScriptEngine; // JavaScript Engine of Browser
}

AgentOSInfo

interface AgentOSInfo {
  name: string; // Operating system name (window, mac, ios, android, etc.)
  version: string; // Operating system version
  majorVersion: number; // Major version number
}

JavaScriptEngine

// Supported browsers: Google Chrome, MS Edge, Opera, Naver Whale, Firefox, Apple Safari, OpenAI Atlas
// OpenAI Atlas is a Chromium-based browser that uses v8.
type JavaScriptEngine =
  | 'v8'
  | 'spidermonkey'
  | 'javascriptcore'
  | 'rhino'
  | 'chakra'
  | 'unknown';

Supported Operating Systems

• Windows: Windows 10, Windows 11, Windows Phone, etc.
• macOS: All versions
• iOS: All versions
• Android: All versions

Features

• User-Agent Client Hints API Priority: Provides more accurate browser information
• Fallback Support: Works reliably on legacy browsers
• TypeScript Support: Complete type definitions provided
• Lightweight: Fast loading with minimal dependencies
• Mobile Support: Perfect support for mobile browsers and WebView environments