What Is My User Agent
View the exact user agent string your browser sends to websites
What the What Is My User Agent Tool Does
Each time your browser asks a website for a page, it introduces itself with a line of text called the user agent string. It looks cryptic, with names like Mozilla and AppleWebKit appearing in browsers that have nothing to do with them, but it carries useful information about your browser, operating system and device. The What Is My User Agent tool on WebTOOLkt reads the string your browser is sending and shows it in full, ready to copy.
Developers use it for testing, testers use it to document environments and curious users use it to see what their browser reveals.
How to Use the Tool
- Open the page in the browser or device you want to check.
- Read the user agent string displayed.
- Copy it using the copy control, or select the text manually.
- Paste it into a bug report, a testing spreadsheet or a configuration that needs the string.
- Open the page again after changing settings or switching to mobile mode to see how the string changes.
How to Read a User Agent String
A typical string is a chain of tokens, each in a pattern such as name, slash and version. Reading from left to right you will often find:
- A legacy product token. Almost every browser still starts with a Mozilla token for historical compatibility, which is why the beginning looks identical across browsers.
- Platform details in brackets. The operating system, sometimes the device type or processor architecture.
- The rendering engine. Names such as AppleWebKit, Gecko or Blink-related tokens identify how the page is drawn.
- The browser and version. Often near the end, for example Chrome, Firefox, Safari or Edge followed by a number.
- Mobile markers. The word Mobile or a phone model typically signals a handset.
The exact definition and history are covered in the MDN User-Agent reference.
Why User Agents Matter
- Compatibility testing. Developers verify that pages work for the browsers their audience uses.
- Analytics. Reports on device and browser share often start from user agent data.
- Bot and crawler identification. Search engine crawlers announce themselves with their own strings. Google lists its crawlers in its crawler overview, and you can use the string to write robots.txt rules.
- Serving mobile pages. Some sites adjust content depending on the detected device.
- Security monitoring. Unusual or fake strings in server logs can point to scraping or attack attempts.
Privacy and Reduced User Agents
Because the string can contribute to browser fingerprinting, major browsers have been reducing the detail it contains, freezing parts of the version and platform information. Sites that need more detail are encouraged to use client hints, which let the browser share specific data on request. The change is explained in the MDN client hints guide. If your string seems vague, that is normal.
Remember that any user agent can be faked. Extensions and developer tools let you change it, so do not rely on it for security decisions.
Changing Your User Agent for Testing
- Open your browser's developer tools.
- Find the device or network conditions panel, where an option to override the user agent usually exists.
- Pick a preset such as a phone or tablet, or enter a custom string.
- Reload the page you are testing.
- Check this tool to confirm the change took effect.
This is a convenient way to see mobile layouts, but real device testing is still more reliable.
Why Use This Tool Instead of Other Options
Finding the user agent manually means opening developer tools and searching for it. The What Is My User Agent tool shows it immediately, free and without installation. It works with What Is My Browser, What Is My Screen Resolution and Get HTTP Headers on WebTOOLkt, so you can build a complete picture of a client environment quickly.
Related WebTOOLkt Tools
- What Is My Browser to see your browser name and version in plain language.
- What Is My Screen Resolution to check your display size.
- Screen Resolution Simulator to preview pages at different sizes.
- Get HTTP Headers to read the headers a server returns.
- Robots.txt Generator to write rules for crawlers.
- What Is My IP to see your public IP address.
Useful External Resources
Frequently Asked Questions
Why does every user agent start with Mozilla?
It is a historical compatibility habit that browsers have kept.
Can websites identify me from my user agent?
On its own it is not personal, but combined with other signals it can contribute to fingerprinting.
Can I change my user agent?
Yes, using developer tools or extensions, mainly for testing.
