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User-Agent Parser

Parse a bounded User-Agent string into browser, OS, platform, engine, product-token, and bot-signature evidence with explicit uncertainty.

LocalNo retention

Reviewed July 13, 2026

Guide, examples, and validation Show

About this tool

Inspect a User-Agent header as self-declared compatibility evidence, while keeping spoofing, browser reduction, and bot-verification limits visible.

  • Uses the MIT-licensed Bowser 2.14.1 parser for browser, operating-system, platform, device, and rendering-engine interpretation.
  • Separates named and generic bot-token matches from verified crawler identity, and exposes the exact matched token.
  • Rejects multiline and oversized inputs, preserves a source snapshot, blocks stale export, and downloads a versioned JSON evidence report.

How to use UA Parser

Parse a bounded User-Agent string into browser, OS, platform, engine, product-token, and bot-signature evidence with explicit uncertainty.

When this tool is useful

  • Uses the MIT-licensed Bowser 2.14.1 parser for browser, operating-system, platform, device, and rendering-engine interpretation.
  • Separates named and generic bot-token matches from verified crawler identity, and exposes the exact matched token.
  • Rejects multiline and oversized inputs, preserves a source snapshot, blocks stale export, and downloads a versioned JSON evidence report.

Examples you can test

Load an example, compare the result with the expected output, then replace it with your own input.

Inspect a browser user agent

Example input

Mozilla/5.0 ... Chrome/126.0 Safari/537.36

Expected output

Browser: Chrome, engine: Blink/WebKit-style token, platform details

Useful for debugging support reports, analytics anomalies, and browser-specific issues.

Identify crawler-like traffic

Example input

Mozilla/5.0 compatible; Googlebot/2.1; +http://www.google.com/bot.html

Expected output

Crawler-style user agent details

User-agent strings can be spoofed, so use them as a clue rather than proof of identity.

Validation checklist

  • Do not rely on user-agent strings alone for security decisions.
  • Expect spoofed, outdated, or incomplete user-agent values.
  • Pair user-agent review with headers, IP ranges, logs, or feature detection when accuracy matters.

Frequently asked questions

Does this tool use any external parsing library?

Yes. It uses the MIT-licensed Bowser 2.14.1 parser locally in your browser. No parsing API receives the User-Agent string.

Can it detect bots and crawlers?

It can report known or generic bot tokens and the matched text, but a token is not proof of crawler identity. Use authoritative reverse DNS, forward DNS, IP ranges, and request evidence when verification matters.

Why does my browser show as Chrome when I use Brave or Edge?

Chromium-family browsers may omit or reduce brand and platform details. Brave commonly masks its brand, while Edge normally exposes an Edg token. A User-Agent alone cannot recover information the browser did not send.

Is my user-agent string sent to any server?

No. All parsing happens entirely in your browser. Nothing is uploaded or transmitted.

What rendering engines does the parser identify?

Bowser can interpret common engine tokens such as Blink, Gecko, WebKit, Trident, Presto, and EdgeHTML. Some User-Agent strings expose only an engine name or no recognized engine version.

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