User Agent Parser Online

User Agent String Parser

This user agent parser online extracts browser, OS, device, and engine details from any UA string—useful for debugging, analytics, and bot detection. A User Agent (UA) string is a piece of text that browsers include in HTTP request headers to identify the client.

What User Agent Strings Are Used For

1. Browser Detection: Websites can serve content optimized for a specific browser based on the UA
2. Analytics: Site administrators can understand which browsers and device types their visitors use
3. Content Negotiation: Servers can deliver the most appropriate content version based on client capabilities
4. Bot Filtering: Some websites may block or rate-limit access from certain User Agents

Note: User Agent strings can be modified by the client, so they should not be fully relied upon to determine the true identity of a client.

Input a User Agent

When you open the tool, the input field is automatically populated with your current browser's User Agent string. You can also manually paste a UA string from any other source for parsing.

To get the UA from browser DevTools:

1. Press F12 or Cmd+Option+I (macOS) to open Developer Tools
2. Switch to the Console panel
3. Type navigator.userAgent and press Enter, then copy the output

You can also find the User-Agent field in the Network panel by clicking on any request and checking the Headers tab.

Understanding the Parsed Results

After pasting a UA string, the tool breaks it down into the following dimensions:

• Browser: Name and version, e.g., Chrome 120, Safari 17.2, Firefox 121
• Operating System: System name and version, e.g., Windows 11, macOS 14.2, Android 14, iOS 17
• Device Type: Desktop, mobile, or tablet. Some UA strings can also identify the specific device model (e.g., iPhone, Samsung Galaxy)
• Engine: Rendering engine information, e.g., Blink, WebKit, Gecko

Note that UA string formats are not standardized. For historical compatibility reasons, browsers often include identifiers of other browsers in their UA strings. For example, Chrome's UA contains Safari — this is normal behavior.

Common Use Cases

Frontend Debugging

When a user reports a display issue in a specific environment, ask them to provide their UA string. Paste it into the tool to quickly identify the browser and OS version and determine whether it's a compatibility problem.

Data Analysis

When analyzing website access logs, paste a UA from the logs to confirm the device type and browser version for a given record, helping you understand traffic distribution.

Bot Identification

Some crawlers and bots have distinctive UA formats (e.g., Googlebot, Bingbot). Paste a suspicious request's UA into the tool to quickly determine whether it's a real user or a bot.

Testing and Validation

When developing responsive pages, compare parsed results from different device UAs to verify that your UA detection logic is working correctly.

FAQ

Q: Can User Agent strings be spoofed?

Yes, User Agent strings can be freely spoofed by the client. Browser extensions, command-line tools (like curl), and web crawlers can all set arbitrary User Agent values. Therefore, UA strings should not be used as the basis for security policies — they are only suitable for non-security-sensitive use cases such as analytics and content adaptation. For browser compatibility checks, feature detection is recommended over User Agent sniffing.

Q: Why are User Agent strings so long?

This is a historical legacy. Early web servers would check the User Agent to determine whether a browser supported certain features. Newer browsers started including older browser identifiers in their UA strings to avoid being rejected by these servers. For example, Chrome's User Agent includes Mozilla, AppleWebKit, and Safari — all to maintain compatibility with server-side logic that checks for specific keywords. This "impersonation" behavior has been inherited through generations, causing UA strings to grow increasingly verbose.

Q: Are modern browsers still using User Agent strings?

Yes, but UA strings are gradually being phased out. Google has proposed User-Agent Client Hints (UA-CH), a structured, on-demand approach designed to replace the traditional User Agent string and reduce passive fingerprinting. Chrome has already begun freezing certain parts of the UA string (such as the platform version), and may simplify it further in the future. However, due to backward-compatibility requirements, fully removing User Agent strings will take a long time — for now, it remains one of the primary ways to obtain client information.