Dev

Random User Agent Generator

A User-Agent string is a short HTTP header sent with every browser request, telling the server what browser, operating system, and device made the call. The random User-Agent generator on this page produces realistic UA strings for desktop browsers, mobile devices, tablets, and bots — formatted exactly as real clients send them. Whether you're building a web scraper, stress-testing a WAF, or validating device-detection middleware, having a pool of authentic-looking strings is essential. Developers commonly need varied UA strings because production traffic includes dozens of browser and OS combinations. A parser tuned only to Chrome on Windows will fail silently when an iOS Safari or Samsung Browser string arrives. Generating a broad sample lets you stress your parsing and routing logic against edge cases before they reach production. The generator lets you control both volume (up to as many strings as you need) and device category — desktop, mobile, tablet, or crawler/bot. Filtering by device type is useful when you're specifically testing responsive server-side rendering logic or verifying that your rate limiter treats known bot signatures differently from browser traffic. Each output string follows the real-world format: Mozilla/5.0 compatibility token, platform details, and browser engine comment, mirroring strings from Chrome, Firefox, Safari, Edge, Googlebot, and others. You can drop them directly into HTTP client configurations, test fixtures, or seed data files.

How to Use

  1. Set the Count field to the number of UA strings you need — start with 10-20 for a varied test sample.
  2. Choose a Device Type from the dropdown to filter results to desktop browsers, mobile, tablet, or bot crawlers.
  3. Click Generate to produce the list of User-Agent strings matching your criteria.
  4. Copy individual strings or the full list and paste them into your test fixtures, HTTP client config, or seed data file.
  5. Re-generate as many times as needed — each run produces a fresh randomised set within the selected device category.

Use Cases

  • •Seeding test fixtures for User-Agent parser unit tests
  • •Rotating UA strings in a web scraper to avoid trivial fingerprinting blocks
  • •Verifying device-detection middleware routes mobile users correctly
  • •Testing WAF rules that block or flag suspicious bot signatures
  • •Simulating Googlebot and Bingbot traffic in server-side rendering previews
  • •Load-testing analytics pipelines that classify sessions by browser and OS
  • •Generating sample data for browser-compatibility reporting dashboards
  • •Validating rate-limiter logic differentiates bots from real browser clients

Tips

  • →Generate separate batches per device type and combine them in a weighted ratio (e.g. 60/30/10 desktop/mobile/bot) to mirror realistic traffic.
  • →When testing a UA parser, deliberately include bot strings alongside browser strings — many parsers misclassify obscure crawler UAs as desktop browsers.
  • →Paste generated strings into https://developers.whatismybrowser.com to verify your parser's output matches the expected classification.
  • →For scraper rotation testing, generate at least 50 unique strings — repeating the same handful of UAs too quickly is itself a detectable signal.
  • →If you're testing Googlebot-specific server behaviour, filter to Bot type and verify your server returns the same content it would to a standard browser (cloaking violates Google's guidelines).
  • →Freeze a generated set in your test fixtures rather than regenerating on every test run — stable fixtures make failures reproducible and diffs readable.

FAQ

What is a User-Agent string?

A User-Agent (UA) string is an HTTP request header that identifies the client software — browser name, version, rendering engine, and operating system. Servers use it to tailor responses, log traffic sources, and enforce access rules. Every browser, crawler, and API client sends one automatically with each request.

Are these generated User-Agent strings real or fake?

They are synthetic but structurally authentic. Each string follows the exact token format used by real browsers and bots, including correct Mozilla/5.0 prefixes, platform blocks, and engine comments. Version numbers are randomised within plausible ranges, so they resemble production traffic without being copied from a specific live device.

Can I use these strings for actual web scraping?

You can use them to test your scraper's UA rotation logic in development. For production scraping, be aware that sites may cross-check UA strings against TLS fingerprints, header ordering, and JavaScript behaviour — rotating UA strings alone is rarely sufficient to avoid detection, and you should comply with each site's terms of service.

How do I parse User-Agent strings in my code?

Use a dedicated library rather than regex: ua-parser-js or bowser for JavaScript, user-agents or httpagentparser for Python, and DeviceDetector for PHP. These libraries maintain updated regex databases covering thousands of real UA patterns and are far more reliable than hand-rolled parsers.

What does the Device Type filter actually change?

Selecting a device type restricts output to UA strings from that category. 'Mobile' returns smartphone UAs like Chrome on Android or Safari on iOS. 'Bot' returns crawler strings like Googlebot or Bingbot. This lets you isolate specific traffic types when testing routing, analytics, or access-control logic.

How many User-Agent strings should I generate for testing?

For parser unit tests, 20-50 strings covering mixed device types gives reasonable edge-case coverage. For load or integration tests simulating realistic traffic distribution, aim for at least 100 unique strings — roughly 60% desktop, 30% mobile, 5% tablet, and 5% bot — to mirror average production traffic ratios.

Do browsers actually send their real User-Agent, or can it be spoofed?

Any client can send an arbitrary UA string — there is no cryptographic verification. This is why security logic should never rely solely on the UA header for access control. It is useful for analytics, optimisation hints, and soft filtering, but must be combined with other signals for anything security-critical.

What is User-Agent Client Hints and will it replace UA strings?

User-Agent Client Hints (UA-CH) is a newer Chrome/Edge API that sends structured device data via Sec-CH-UA headers rather than a single monolithic string. Chrome has begun freezing and reducing UA string detail to improve privacy. Testing both legacy UA strings and Ch-Hints handling is increasingly important for forward-compatible parsers.