User-Agent Checker – Auto-Detect Browser and OS Info

Instantly detect and view your current browser’s User-Agent string as soon as you visit the page.
Skip opening complex developer tools and copy your detailed device information with a single click.

This is an essential tool for diagnosing cross-browser compatibility issues and web debugging on both mobile and desktop environments.
Easily identify your browser version, rendering engine, and OS to optimize your website.

If you also need to check your network status during debugging, use Vivoldi’s IP Address Lookup tool.

User-Agent Checker – Auto-Detect Browser and OS Info

Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)

Why ‘User-Agent’ verification is essential for successful web development and debugging

When developing a website, you often encounter cross-browsing issues where CSS or JavaScript behaves differently depending on the browser (Chrome, Safari, Firefox, etc.) or operating system (Windows, macOS, Mobile) environment.
The ‘Vivoldi’ User-Agent checker is an essential utility to quickly and accurately diagnose these fragmentation issues.

  • Instant Response to Browser Updates: Instantly check the subtly changed rendering engine info and User-Agent strings whenever major browsers update their versions, preventing logic errors in advance.
  • Mobile and Desktop Environment Testing: When debugging how a web page should render based on the connected device, you can grasp the exact access environment info at a glance without opening cumbersome developer tools.
  • Easy Data Copying and Application: Copy the identified long string to your clipboard with a single click and paste it directly into server log analyzers or code editor conditional statements to maximize workflow efficiency.

Have questions?
Check the FAQ.

A User-Agent is a string automatically sent by your browser when accessing a website, including browser type & version, rendering engine, and operating system details.

Common browser examples: Chrome, Edge, Safari, Firefox, Naver Whale, etc.

Example: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36

  • Usage: Site analytics, customized UI, debugging, service quality improvements.
  • Note: Strings may vary with browser & OS updates, so they have limitations for absolute identification.

User-Agent data identifies browser, operating system & device, helping websites deliver optimized experiences tailored to each environment.

  • Customized UI: Platform-specific features, linking to app stores (App Store & Google Play, etc.).
  • Analytics & Marketing: Visitor environment analysis, marketing strategy development.
  • Security & Operations: Detecting abnormal access, debugging browser-specific issues, strengthening policies.

While browser compatibility has improved significantly, User-Agent data remains vital for optimization and site management.

For everyday browsing there’s no issue, but in cases like web development & app integration & site error diagnosis & browser compatibility testing, you may need to verify the actual User-Agent value.

  • When a site feature doesn’t work properly.
  • When customer support requests your “User-Agent value.”
  • When developing or testing apps or browser extensions.

With this tool, you can instantly view, copy, and share the real User-Agent, making it essential for troubleshooting, service improvement, technical support, and development collaboration.