User-Agent Parser

How to Use the Free Client-Side User-Agent Parser

Every HTTP request advertises itself with a User-Agent string, and reading one by eye is a slog of nested product tokens. This parser breaks the string apart into plain-language fields:

Parsing runs locally in your browser. Your User-Agent strings are never transmitted anywhere.

1. Copy a User-Agent string from your browser, server logs, or HTTP headers and paste it into the input field.
2. Review the parsed output, which identifies the browser, version, operating system, and device type.
3. Expand the version breakdown to see detailed numbers for the browser, engine, and OS.
4. Click any individual parsed field to copy it to your clipboard for use in reports or debugging.

When to Use User-Agent Parser

Analysts and site owners work through server logs full of these strings, trying to answer basic questions: what browsers are our visitors using, what operating systems dominate, and how much of the traffic is mobile. A parser turns a wall of logs into readable categories, and the browser, OS, and device-type fields map directly onto the breakdowns you would want for a traffic report.

Developers debugging browser-specific rendering issues reach for it when a bug report says a page works in one browser and not another. Verifying exactly which browser version and operating system the failing request came from, straight from the raw header, is the first step in reproducing the problem. The version breakdown is useful here because a fix that works in Chrome 120 may not exist in Chrome 114, and the log often does not make that obvious.

The device-type detection matters for teams serving different layouts. Many sites tailor markup and behavior for mobile, tablet, and desktop, and confirming that a particular string is classified correctly tells you whether your detection logic is working as intended. Bot and crawler detection is a related use: identifying crawler traffic in your logs explains request patterns and lets you tell real users apart from automated visitors.

User-Agent Parser Tips and Best Practices

1. Treat User-Agent strings as untrusted input. They are sent by the client and trivially spoofable, so never use parsing alone for security decisions like access control or payment eligibility.
2. Do not assume the version numbers are honest. Privacy tools and some browsers randomize or obscure the string, so a value reporting Chrome 120 may actually be something else.
3. Keep the regex-based limits in mind. Common browsers and OS patterns parse cleanly, but less common or heavily modified strings may come back as unknown.
4. Use the copy-field feature to move a single parsed value into a report or a spreadsheet without retyping it.

Why Client-Side Privacy Matters for server log analysis and device targeting

User-Agent strings are part of request metadata, and the ones you analyze can identify individuals through browser fingerprints and device details. Processing them in a web service that logs its inputs builds a profile of your traffic and your employees' environments, all of it on someone else's infrastructure.

Because parsing happens entirely in your browser, the strings you analyze never leave your device. You can study your server logs or inspect a header from your own request without that metadata being collected or stored elsewhere.