User-Agent Parser & Generator

Parse user-agent strings to identify browser, OS, device and engine, or generate realistic ones

Paste any user-agent string to parse its components

Generate a user-agent string

Build realistic browser or crawler user-agents for testing scrapers, APIs and device detection. Paste one into the parser above to check how it is detected.

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Parsing User-Agent Strings to Identify Browsers, OS, and Devices

The User-Agent HTTP header identifies the client making a request — but its format is a historical accumulation of compatibility hacks rather than a clean specification. Modern user-agent strings contain nested browser identifiers, rendering engine versions, platform tokens, and mobile indicators packed into a single string that is difficult to parse manually. The User-Agent Parser analyzes any UA string to extract browser name and version, operating system, device type (desktop, mobile, tablet, bot), and rendering engine using pattern matching against known token formats.

Paste any user-agent string to instantly see its components broken down: which browser and version, which OS and version, whether it is a mobile or desktop device, which rendering engine powers it, and whether it is a known bot or crawler. This is essential for debugging browser-specific issues, analyzing access logs, filtering bot traffic, and understanding your audience's technology profile. All parsing happens client-side using regex patterns.

Browser and Version Detection

The parser identifies browsers across all major engines and platforms:

Version extraction handles the varying formats across browsers — Chrome uses simple "Chrome/120.0" while Safari uses "Version/17.0" alongside an AppleWebKit version that is not the browser version.

Device and OS Classification

Operating system and device type detection enables platform-specific debugging:

Bot and Crawler Identification

Distinguishing bots from real users is essential for analytics and access control:

Bot detection helps separate real user traffic from automated requests in analytics, implement bot-specific responses (pre-rendered pages for SEO bots), and identify potential scraping or abuse patterns. The parser also detects spoofed bot user-agents by checking for inconsistencies in the token ordering and version numbers that real crawlers use, helping identify impersonation attempts that claim to be Googlebot but lack the correct token structure.

Understanding bot traffic composition helps infrastructure teams plan capacity correctly — a site receiving 60% bot traffic may appear to have double the actual user load if bots are not filtered from request metrics.

Code Examples

User-Agent Parse Results

# Input:
Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Mobile/15E148 Safari/604.1

# Parsed result:
# Browser:  Safari 17.0
# Engine:   WebKit 605.1.15
# OS:       iOS 17.0
# Device:   Mobile (iPhone)
# Type:     Real user (not a bot)

# Another example:
# Input: Googlebot/2.1 (+http://www.google.com/bot.html)
# Browser:  Googlebot 2.1
# Engine:   Unknown
# OS:       Unknown
# Device:   Bot
# Type:     Search engine crawler (Google)

Frequently Asked Questions

Can I also generate user-agent strings?

Yes. The generator below the parser builds browser user-agents for a chosen browser, operating system and device type, or crawler user-agents such as Googlebot and Bingbot, up to 50 at a time.

What information can be extracted from a user-agent string?

A user-agent string typically contains the browser name and version, operating system and version, device type (desktop, mobile, tablet, or bot), and the rendering engine (Blink, Gecko, WebKit, or Trident). This tool extracts all of these components.

Why do some browsers report multiple browser names in the user-agent?

Modern browsers include legacy tokens for compatibility. For example, Chrome includes "Safari" and "AppleWebKit" in its UA string because early websites checked for these tokens. Edge includes "Chrome" because it uses the same engine. The parser handles this by checking browsers in specificity order: Edge → Opera → Chrome → Firefox → Safari.

Is my user-agent string sent to any server?

No, all parsing happens entirely in your browser using client-side JavaScript. Your user-agent string never leaves your device, ensuring complete privacy.

How does the parser detect bots and crawlers?

The parser checks for known bot signatures like Googlebot, Bingbot, YandexBot, DuckDuckBot, and others before attempting browser detection. Bot user-agents typically include the bot name followed by a version number.

What are the privacy implications of user-agent strings?

User-agent strings can contribute to browser fingerprinting, allowing websites to track users without cookies. This is why browsers are gradually reducing the information in UA strings through initiatives like User-Agent Client Hints (UA-CH). Chrome has been freezing parts of the UA string since 2022.