User-Agent Generator
Generate realistic browser and bot user-agent strings for testing scrapers, APIs, and device simulation
Generating Realistic User-Agent Strings for Testing
User-Agent strings identify the client making HTTP requests — but generating realistic ones for testing requires understanding the complex layering of browser, engine, platform, and compatibility tokens that modern browsers include. Whether you need to test how your server responds to mobile devices, verify bot detection logic, simulate specific browser versions for compatibility testing, or generate diverse UA strings for scraper development, a User-Agent Generator produces correctly formatted strings that match real browser patterns without requiring access to actual devices.
Select a browser, operating system, and device type to generate a realistic user-agent string matching that combination. Generate bot/crawler user-agents for testing Googlebot, Bingbot, and social media crawler detection. All generation uses hardcoded version data matching real browser release patterns — no external dependencies or API calls required.
Browser and Platform Combinations
The generator produces UA strings for all major browser/platform combinations:
- Desktop browsers: Chrome, Firefox, Safari, Edge on Windows, macOS, and Linux
- Mobile browsers: Chrome Mobile, Safari iOS, Samsung Internet, Firefox Mobile on Android and iOS
- Tablet variants: iPad Safari, Android tablet Chrome with appropriate platform tokens
- Legacy browsers: Internet Explorer 11, Edge Legacy for compatibility testing
Each generated string includes the correct engine tokens (Blink/Gecko/WebKit), platform identifiers (Windows NT version, macOS version, Linux kernel), and browser-specific tokens in the exact order real browsers use.
Bot and Crawler User-Agents
Testing bot detection and rendering requires accurate crawler UA strings:
- Search engines: Googlebot (desktop and mobile), Bingbot, Yandex, Baidu Spider, DuckDuckBot
- Social media: FacebookExternalHit, TwitterBot, LinkedInBot, WhatsApp
- Monitoring: Pingdom, UptimeRobot, GTmetrix, PageSpeed Insights
- Feed readers: Feedly, Feedbin, NewsBlur
Bot user-agents are particularly important for testing server-side rendering (SSR) logic that serves pre-rendered pages to crawlers, and for verifying that rate limiting or access controls correctly identify and handle automated traffic.
Testing Use Cases
Realistic user-agent generation serves multiple testing workflows:
- Responsive design testing: Verify server-side device detection returns correct layouts for mobile, tablet, and desktop UAs
- Feature detection: Test that your application serves appropriate polyfills or fallbacks for older browser versions
- Analytics testing: Verify that your analytics system correctly categorizes traffic by browser, OS, and device type
- Bot handling: Test that SEO bots receive pre-rendered content while real users get the interactive version
- Rate limiting: Verify that your rate limiter does not treat different UAs from the same IP as different users
- A/B testing verification: Confirm that experiments assign users consistently regardless of user-agent string variations
For web scraping development, rotating through diverse realistic user-agent strings helps avoid detection by anti-bot systems that flag repeated identical UA patterns. The generator produces strings with version numbers matching real browser release schedules, making them indistinguishable from genuine browser traffic.
Code Examples
Generated User-Agent String Examples
# Desktop Chrome on Windows 11:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36
# Mobile Safari on iPhone (iOS 17):
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
# Firefox on Ubuntu Linux:
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:123.0) Gecko/20100101 Firefox/123.0
# Googlebot (Desktop):
Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
# Googlebot (Mobile — Smartphone):
Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Mobile Safari/537.36 (compatible; Googlebot/2.1)
# Using in HTTP requests:
curl -H "User-Agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_0...)" https://example.comFrequently Asked Questions
What is a user-agent string and why would I generate one?
A user-agent string is an HTTP header that identifies the client software making a request — typically the browser, operating system, and device type. Developers generate custom user-agent strings for web scraping, API testing, browser compatibility testing, and simulating different devices without needing physical hardware.
Are the generated user-agent strings realistic?
Yes. This tool uses real platform tokens, version numbers from recent browser releases, and authentic formatting patterns. The generated strings are structurally identical to those sent by actual browsers and bots, making them suitable for testing and development.
Is generating user-agent strings legal?
Generating user-agent strings is legal and a standard practice in software development. However, using them to bypass access controls, violate terms of service, or impersonate bots for malicious purposes may have legal implications. Always use generated UAs responsibly and in compliance with target website policies.
What is the difference between browser mode and bot mode?
Browser mode generates user-agent strings that mimic real web browsers (Chrome, Firefox, Safari, Edge, Opera) on various operating systems and devices. Bot mode generates crawler user-agent strings used by search engines like Google, Bing, Yandex, and DuckDuckGo to index web content.