Free User-Agent parser — break a UA string into browser, OS, device and CPU

Parsed with ua-parser-js entirely in your browser — nothing is uploaded.

🕵️ User-Agent Parser — Free Online Tool

Decode a User-Agent string into browser, OS and device, free. The User-Agent is an HTTP request header (defined in RFC 9110) that identifies the browser, rendering engine, operating system and device making a request. This parser breaks a raw, hard-to-read UA string into those readable parts — entirely in your browser.

🚀 Why use this User-Agent Parser tool?

It turns a cryptic User-Agent string into a clear breakdown of browser, version, engine, operating system and device type. 100% free, no registration, and complete privacy — everything runs locally in your browser, so your data never touches a server.

Key Features

🔍Readable breakdown

Identify the browser and version, layout engine, OS, and whether it's mobile or desktop from one UA string.

📋Paste or use yours

Paste any User-Agent to analyse it, or inspect your own browser's UA for quick debugging.

🔒100% private

Parsing runs locally in your browser; the string you paste is never uploaded or stored.

🆓Free, no signup

Unlimited parsing with no account, on desktop and mobile.

Popular Use Cases

Web development

  • Debug device-specific bugs
  • Check what a client reports
  • Test responsive behaviour

Analytics & support

  • Interpret a UA from logs
  • Identify a user's setup
  • Reproduce an environment

QA & security

  • Spot spoofed or bot UAs
  • Audit access logs
  • Verify crawler identity

What It Handles

Identifies

  • Browser & version
  • Rendering engine
  • Operating system

Device

  • Mobile vs desktop
  • Device hints
  • Bot/crawler hints

Workflow

  • Paste any UA
  • Copy results
  • Runs offline

Sources & References

Frequently Asked Questions

What is a User-Agent string?

It's an HTTP header browsers and apps send to identify themselves — including the browser name and version, rendering engine, and operating system. Servers use it to adapt responses, and analytics tools use it to categorize traffic.

Can I trust the User-Agent?

Not fully. The UA is set by the client and can be freely changed or spoofed (bots often impersonate browsers), so treat it as a hint, not proof. For critical decisions, use feature detection instead.

Why do all UAs contain 'Mozilla/5.0'?

It's a historical artifact: browsers added 'Mozilla' decades ago for compatibility with servers that checked for it, and the convention stuck. It no longer indicates the actual browser.

Is my User-Agent uploaded anywhere?

No. Parsing happens entirely in your browser; nothing you paste leaves your device.

Should I rely on UA parsing for features?

Prefer feature detection (checking if an API exists) over UA sniffing — it's more reliable and doesn't break when browsers change their UA. UA parsing is best for analytics and debugging.

🎓 Pro Tips

  • Tip 1: Use feature detection, not UA sniffing, to decide what code to run — UA strings change often and are easily spoofed.
  • Tip 2: Modern browsers freeze and reduce UA detail (UA-Client-Hints) for privacy, so newer strings carry less version detail than older ones.
  • Tip 3: The User-Agent header is specified in RFC 9110 §10.1.5 — https://www.rfc-editor.org/rfc/rfc9110.