Guide to Modifying User-Agents in Chrome, Edge, Safari & Firefox

  • June 10, 2024
  • SEO
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Whether you are an SEO expert, marketer, or web developer, changing your browser’s user-agent frequently becomes a necessary task. This practice allows you to test various scenarios across different devices and browsers.

For instance, consider running a campaign specifically for macOS users. By changing your browser’s user-agent, you can verify if your campaign correctly targets macOS users and not others, such as those on Linux.

For web developers, altering user-agents is a routine process to test website behavior across different devices and browsers.

Understanding User-Agents

A user-agent is an HTTP request header string identifying the browser, application, or operating system connecting to the server. It is not limited to browsers; bots and crawlers like Googlebot and Google AdSense also utilize user-agents.

Screenshot by author, May 2024

How to Change Your Browser’s User-Agent

The process of changing the user-agent is known as user-agent spoofing. This involves sending a different user-agent HTTP header than what the client truly is. Although “spoofing” might sound alarming, it is a harmless activity often necessary for testing and troubleshooting purposes.

How to Change Your User-Agent in Chrome & Edge

Given that Microsoft Edge now uses Chromium, the settings for both Chrome and Edge are identical.

Step-by-Step Guide

1. Open Developer Tools:

Right-click anywhere on the webpage and select Inspect. Alternatively, use Ctrl+Shift+I on Windows or Cmd+Opt+J on Mac.

Chrome Screenshot by author, May 2024

2. Navigate to More Tools > Network Conditions:

Click on the three vertical dots in the upper-right corner and choose More Tools, then Network Conditions.

Chrome settingsScreenshot by author, May 2024

3. Uncheck Select Automatically Checkbox:

Under the Network Conditions panel, uncheck the Select Automatically checkbox to manually specify a user-agent.

Chrome instructionScreenshot by author, May 2024

4. Choose or Enter a User-Agent:

Select a user-agent from the built-in list. If the desired user-agent is not listed, enter a custom user-agent string in the field below. For instance, enter the following string to mimic Googlebot:

Mozilla/5.0 (compatible; Googlebot/2.1; +
Chrome settings for user agentScreenshot by author, May 2024

This is particularly useful for SEO professionals to detect cloaking, a technique where websites show different content to search engines than to users.

Alternatively, you can use the Chrome extension User-Agent Switcher and Manager.

How to Change Your User-Agent on Safari

1. Open Preferences:

Go to Safari > Preferences.

Safari browser preferencesScreenshot by author, May 2024

2. Enable Develop Menu:

Under the Advanced tab, check Show Develop menu in menu bar.

Settings on MacScreenshot by author, May 2024

3. Navigate to Develop > User-Agent:

In the menu bar, go to Develop and select User-Agent. You can choose from a predefined list or enter a custom user-agent by selecting “Other…” from the dropdown menu.

Safari's develop menu. User agentScreenshot by author, May 2024

How to Change User-Agent in Firefox

While Firefox allows user-agent changes through its built-in settings, the process is not as intuitive as in Chrome or Safari. As a more straightforward alternative, you can use the Firefox add-on User-Agent Switcher.

After installing the add-on, an icon will appear in the upper-right corner of the browser. Click the icon to choose a predefined user-agent or enter a custom string by clicking the pen icon.

Firefox settingsScreenshot by author, May 2024

Another useful extension is the User-Agent Switcher and Manager.

Simplicity & Utility of User-Agent Spoofing

User-agents are easy to spoof, making them an accessible tool for anyone needing to alter them. This is particularly valuable for testing web applications across different devices, ensuring they render correctly on various platforms without requiring multiple physical devices.

However, some issues may arise when testing on emulators, which might not appear on real devices. For comprehensive testing across real devices, consider using services like Browserstack, which offers extensive testing options on virtually all devices.


What is a user agent?

A user agent is an HTTP request header string that identifies the browser, application, or operating system connecting to the server. In addition to browsers, user agents are used by bots and crawlers, such as Googlebot and Google AdSense.

What is user-agent spoofing?

User-agent spoofing occurs when a browser or client sends a different user-agent HTTP header than what it actually is, effectively “faking” its identity.

How does changing the user-agent help SEO professionals?

SEO professionals may find changing the user-agent to be a critical part of their audit process for several reasons:

  • Identifying cloaking issues: Mimicking different user-agents, such as Googlebot, helps uncover if a website presents different content to search engines than users, violating search engine guidelines.
  • Ensuring compatibility across various browsers and devices.
  • Optimizing user experience by understanding how content is rendered on different systems.
  • Pinpointing browser-specific issues for debugging.
  • Ensuring website integrity and performance through quality assurance.

Can changing your browser’s user-agent pose a security risk?

No, changing your browser’s user-agent, commonly referred to as user-agent spoofing, is not inherently risky. While “spoofing” sounds malicious, in the context of user-agents, it is a harmless practice useful for testing and troubleshooting.

More Resources:

Featured Image: /Shutterstock

All screenshots taken by author, May 2024

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