User Agent Parser
Parse browser user agent strings.
A User-Agent string is the noisy fingerprint browsers and bots send with HTTP requests. Utilitoo's User-Agent Parser turns that opaque header into structured fields - browser family, operating system, and device class (desktop, mobile, or tablet) - so you can act on it without installing a UA library.
Support engineers paste UA values from tickets to match the customer's environment. QA teams build a small library of real strings to regression-test responsive layouts and feature flags. Analytics and anti-abuse reviewers spot-check whether a reported visit looks like Chrome on Windows, Safari on iOS, or something odd enough to investigate further. Language preference is not in the UA: that lives on Accept-Language, which Locale Converter turns into BCP 47 and POSIX tags.
Paste a raw UA, click Parse, or use "Use my browser" to inspect the current client. Pair with HTTP Header Viewer when you have a full response dump, Locale Converter when the ticket is about date or number format rather than the browser family, Regex Tester when you are writing detection rules, and URL Encoder when reconstructing request examples for docs.
Parsing never leaves your browser. UA strings from customers are not uploaded or logged. Keep a private folder of representative samples from past incidents so you can replay bugs without asking users to re-send screenshots.
User Agent Parser turns a raw User-Agent header into browser, OS, and device-class fields for support, QA, and analytics triage. It runs locally so ticket pastes are not uploaded - still redact cookies if you pasted a larger header block by mistake.
Common use cases
- Decoding a customer UA from a support ticket to match browser and OS before reproducing a bug.
- Building a small library of real UA strings for responsive and feature-flag QA.
- Spot-checking whether analytics traffic looks like mobile Safari, desktop Chrome, or something odd.
- Teaching how compatibility tokens make UA strings long and unreliable as identity.
- Inspecting your current browser via Use my browser when writing detection notes.
Tips & common mistakes
Treat UA output as a hint, not proof of a specific device model. Pair with HTTP Header Viewer when you have a fuller request dump. Language preference is Accept-Language, not the UA - convert those tags in Locale Converter. Save representative samples from past incidents so you can replay bugs without asking customers again. Regex Tester helps when you are drafting detection rules from the structured fields.
Common errors
- Unknown browser - uncommon or bot UAs may not match the built-in family rules.
- Desktop vs mobile mismatch on tablets - confirm with viewport testing, not UA alone.
- Partial paste - truncated headers produce incomplete or Unknown fields.
How to use
- Paste a full User-Agent header value, or click Use my browser.
- Click Parse to extract browser, OS, and device class.
- Copy the fields you need into a ticket, test fixture, or detection rule notes.
Frequently Asked Questions
How do I parse a user agent string online?▼
Paste the full User-Agent header into Utilitoo and click Parse. The tool shows browser, OS, and device class. Use "Use my browser" to inspect the client you are on right now.
What does the user agent parser extract?▼
Browser family (Chrome, Firefox, Safari, Edge, IE), operating system (Windows, macOS, Android, iOS, Linux), and device class (desktop, mobile, tablet), plus the raw string for reference.
Why are user agent strings so long and inconsistent?▼
Browsers add historical compatibility tokens so older servers still serve usable pages. That makes strings long, overlapping, and a poor source of identity - treat them as hints, not proof.
Can I tell mobile from desktop with this parser?▼
Yes for common patterns. Mobile and tablet markers in the UA map to device class. Always confirm with real devices when layout bugs depend on viewport size, not just the UA label.
Does parsing a customer UA upload their data?▼
No. Utilitoo evaluates the string in your browser only. Still redact cookies or auth tokens if you pasted a larger header block by mistake. Language tags from Accept-Language belong in Locale Converter, not this parser.
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