Random User Agent

A random user agent is a user agent string that is selected or generated at random, typically to make a browser, scraper, or automation tool appear as a different browser, operating system, or device with each request or session.

Random user agents are widely used in web scraping, automated testing, security research, and privacy browsing. The goal is to avoid detection by rotating through different browser identities rather than sending the same user agent string with every request.

What Is a User Agent?

Before getting into randomization, it helps to understand what a user agent actually is.

A user agent is a string of text that your browser sends to every website you visit. It tells the server what software is making the request: the browser name, version, operating system, and sometimes the device type. A typical user agent looks like this:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Websites use user agents to serve browser-specific content, handle compatibility issues, and increasingly, to detect bots and automation. If a scraper sends thousands of requests with the identical user agent, that consistency is itself a signal that something automated is running.

Randomizing the user agent changes that string with each request or session, making automated traffic look more like a mix of different real users on different browsers and devices.

What Is a Random User Agent?

A random user agent is any method of selecting a user agent string that is not fixed. This can mean:

• Pulling from a pre-built list of real browser user agents and selecting one at random
• Using a library or API that generates plausible user agent strings dynamically
• Installing a browser extension that rotates your user agent automatically
• Setting user agent rotation in a scraping or automation framework

The “randomness” is the key function. Instead of your tool always identifying as Chrome/120 on Windows, it might identify as Firefox/121 on macOS for one request, Safari/17 on iPhone for the next, and Chrome/119 on Linux after that.

Random User Agent Extensions for Browsers

The easiest way to randomize your user agent for general browsing or light testing is through a browser extension.

Random User Agent for Chrome

Several extensions are available in the Chrome Web Store for user agent switching. The most commonly used ones are simply called “Random User Agent” or “User-Agent Switcher.” They let you set a rotation interval (per session, per request, or manually triggered) and choose from categories of real user agents (Chrome versions, Firefox, Safari, mobile devices, etc.).

To add a random user agent extension to Chrome: open the Chrome Web Store, search “random user agent,” and install one of the top results. After installation, you will see an icon in your toolbar where you can configure rotation settings.

Popular options include:

• Random User Agent Switcher (the most widely downloaded)
• User-Agent Switcher and Manager (more configuration options)

Random User Agent for Firefox

Firefox has several strong options for user agent randomization. The most well-known is the Random User Agent Switcher add-on, available from the official Firefox Add-ons site. It works similarly to the Chrome version, letting you rotate on a timer or switch manually.

To add a random user agent to Firefox: go to addons.mozilla.org, search “random user agent,” and install the add-on. Firefox also supports “User-Agent Switcher” which gives manual control over which user agent you present.

The Firefox random user agent spoofer options tend to have slightly more granular control than Chrome equivalents because Firefox’s extension API allows deeper browser customization.

Random User Agent for Safari

Safari does not have the same extension ecosystem as Chrome or Firefox, which makes user agent randomization more limited. Safari does have a built-in developer option to override the user agent under Develop > User Agent in the menu bar. This is manual, not randomized. For automated rotation in Safari, you need to use the browser’s developer tools or a framework-level solution.

Random User Agent for Opera

Opera is Chromium-based, so most Chrome extensions for random user agents work directly in Opera. Install any Chrome user agent switcher extension and it will function the same way.

Random User Agent for Android

On Android, browser extensions are limited. Firefox for Android supports add-ons and can use the Random User Agent Switcher extension. Chrome on Android does not support extensions. For randomizing user agents on Android at scale, a programmatic approach (Python, Node.js) or a cloud phone setup is more practical than browser extensions.

Random User Agent in Code

For developers, implementing random user agent rotation programmatically is more reliable and scalable than browser extensions.

Python Random User Agent

The most popular library for random user agents in Python is fake-useragent. It pulls from a database of real browser user agents and selects one randomly.

from fake_useragent import UserAgent

ua = UserAgent()

random_agent = ua.random

print(random_agent)

# Output: something like “Mozilla/5.0 (Windows NT 10.0; Win64; x64)…”

For use with requests:

import requests

from fake_useragent import UserAgent

ua = UserAgent()

headers = {“User-Agent”: ua.random}

response = requests.get(“https://example.com”, headers=headers)

For generating a random user agent in Python without a library:

import random

user_agents = [

    “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Chrome/120.0.0.0 Safari/537.36”,

    “Mozilla/5.0 (Macintosh; Intel Mac OS X 14_0) AppleWebKit/605.1.15 Safari/605.1.15”,

    “Mozilla/5.0 (X11; Linux x86_64; rv:121.0) Gecko/20100101 Firefox/121.0”,

]

random_agent = random.choice(user_agents)

Python Requests Random User Agent (Scrapy)

In Scrapy, the standard approach is the scrapy-user-agents middleware, which rotates user agents automatically across requests.

# settings.py

DOWNLOADER_MIDDLEWARES = {

    “scrapy.downloadermiddlewares.useragent.UserAgentMiddleware”: None,

    “scrapy_user_agents.middlewares.RandomUserAgentMiddleware”: 400,

}

This pulls from a list of real user agents and applies one randomly to each request, with no additional code required in your spiders.

Puppeteer Random User Agent

In Puppeteer (Node.js), set the user agent before navigating:

const puppeteer = require(“puppeteer”);

const { randomUseragent } = require(“random-useragent”);

(async () => {

  const browser = await puppeteer.launch();

  const page = await browser.newPage();

  const agent = randomUseragent.getRandom();

  await page.setUserAgent(agent);

  await page.goto(“https://example.com”);

  await browser.close();

})();

The random-useragent npm package provides a curated list of real browser user agents with filtering options (browser type, OS, version range). Install it with:

npm install random-useragent

Selenium Random User Agent

In Selenium with Python:

from selenium import webdriver

from selenium.webdriver.chrome.options import Options

from fake_useragent import UserAgent

ua = UserAgent()

options = Options()

options.add_argument(f”user-agent={ua.random}”)

driver = webdriver.Chrome(options=options)

driver.get(“https://example.com”)

For Selenium with Java or other languages, the same approach applies: set the user agent as a browser option or capability before launching the driver.

Node.js / npm Random User Agent

Install the package:

npm install random-useragent

Basic usage:

const randomUseragent = require(“random-useragent”);

const agent = randomUseragent.getRandom();

// Returns a random user agent string from the built-in database

const chromeAgent = randomUseragent.getRandom(function(ua) {

  return ua.browserName === “Chrome”;

});

// Returns a random Chrome user agent specifically

Golang Random User Agent

In Go, implement rotation by maintaining a slice of user agent strings and selecting randomly:

package main

import (

    “math/rand”

    “net/http”

)

var userAgents = []string{

    “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Chrome/120.0.0.0 Safari/537.36”,

    “Mozilla/5.0 (Macintosh; Intel Mac OS X 14_0) AppleWebKit/605.1.15 Safari/605.1.15”,

    “Mozilla/5.0 (X11; Linux x86_64; rv:121.0) Gecko/20100101 Firefox/121.0”,

}

func getRandomUserAgent() string {

    return userAgents[rand.Intn(len(userAgents))]

}

func main() {

    client := &http.Client{}

    req, _ := http.NewRequest(“GET”, “https://example.com”, nil)

    req.Header.Set(“User-Agent”, getRandomUserAgent())

    client.Do(req)

}

PHP cURL Random User Agent

In PHP with cURL:

<?php

$userAgents = [

    “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Chrome/120.0.0.0 Safari/537.36”,

    “Mozilla/5.0 (Macintosh; Intel Mac OS X 14_0) AppleWebKit/605.1.15 Safari/605.1.15”,

    “Mozilla/5.0 (X11; Linux x86_64; rv:121.0) Gecko/20100101 Firefox/121.0”,

];

$randomAgent = $userAgents[array_rand($userAgents)];

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, “https://example.com”);

curl_setopt($ch, CURLOPT_USERAGENT, $randomAgent);

curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$response = curl_exec($ch);

curl_close($ch);

?>

curl Random User Agent (Command Line)

curl -A “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Chrome/120.0.0.0 Safari/537.36” https://example.com

For scripted rotation in bash:

agents=(

  “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 Chrome/120.0.0.0 Safari/537.36”

  “Mozilla/5.0 (Macintosh; Intel Mac OS X 14_0) AppleWebKit/605.1.15 Safari/605.1.15”

  “Mozilla/5.0 (X11; Linux x86_64; rv:121.0) Gecko/20100101 Firefox/121.0”

)

agent=”${agents[$RANDOM % ${#agents[@]}]}”

curl -A “$agent” https://example.com

Random User Agent in Security Tools

Several security and penetration testing tools support user agent randomization as part of their scan configuration.

ffuf Random User Agent

In ffuf (a fast web fuzzer), set a custom user agent with the -H flag:

ffuf -u https://example.com/FUZZ -w wordlist.txt -H “User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/120.0.0.0”

To rotate across multiple agents, use a script wrapper that calls ffuf with a different -H value each run.

Gobuster Random User Agent

Gobuster supports the –useragent flag:

gobuster dir -u https://example.com -w wordlist.txt –useragent “Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/120.0.0.0”

Nikto Random User Agent

Nikto allows user agent configuration in its config file or via command line:

nikto -h https://example.com -useragent “Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/120.0.0.0”

Nuclei Random User Agent

Nuclei templates can include custom headers. Set the user agent in your template headers section or use the -H flag at runtime:

nuclei -u https://example.com -H “User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/120.0.0.0”

Random User Agent APIs and Online Generators

If you need a quick random user agent without writing code or installing anything, several online tools and APIs generate them on demand.

• Online generators: Search “random user agent generator online” and you will find several tools that output a random real user agent string you can copy and paste. These are useful for quick testing.
• APIs: Some services provide user agent APIs where you can make a request and receive a random user agent string in the response. These are useful when you need to fetch fresh user agents programmatically without maintaining your own list.
• GitHub lists: Several GitHub repositories maintain curated lists of real user agents organized by browser and version. These are useful as source data for your own rotation implementation. Search “random user agent github” to find maintained lists.

The Limits of Random User Agents

Here is where random user agent switching runs into its fundamental problem: the user agent is just one signal among hundreds.

Modern fingerprinting systems collect far more data than the user agent string. Canvas fingerprint, WebGL renderer, screen resolution, installed fonts, timezone, language settings, battery status, hardware concurrency, audio context, WebRTC IP, HTTP header order, and dozens of other signals are collected alongside the user agent.

When you rotate your user agent but keep everything else consistent, you create an obvious inconsistency. You might claim to be a mobile Safari user on iPhone but your screen resolution is 1920×1080 and your WebGL renderer shows a desktop GPU. Detection systems flag this contradiction immediately.

Worse, the browser extensions that randomize user agents often introduce their own fingerprinting signature. The extension itself is detectable. Using a known user agent switching extension tells detection systems that someone is actively trying to hide their identity, which is itself a signal.

This is the core problem with user agent randomization as a standalone privacy or scraping technique: it changes one piece of data while leaving the rest of your fingerprint intact and internally inconsistent.

What Actually Works Instead

For genuine fingerprint protection, the user agent needs to change as part of a consistent, internally coherent fingerprint where all signals align.

This is what Multilogin’s antidetect browser does. Rather than randomly switching one parameter, Multilogin generates complete, internally consistent browser profiles where the user agent, canvas fingerprint, WebGL data, screen resolution, fonts, timezone, and all other detectable signals align correctly with each other. The browser presents as a real, coherent device, not a patchwork of mismatched parameters.

Each browser profile in Multilogin maintains its own consistent fingerprint across sessions. When you use a profile that presents as Chrome 120 on Windows, every single signal the browser emits is consistent with that identity. There are no contradictions for detection systems to catch.

For mobile-specific use cases, Multilogin Cloud Phones go even further. Rather than spoofing a mobile user agent in a desktop browser (which is immediately detectable through dozens of other signals), each cloud phone is a real Android device running in the cloud with genuine hardware identifiers. The user agent, screen data, hardware IDs, GPS, and network connection all correspond to a real physical device because the device is real.

User Agent Randomization vs. Full Fingerprint Management