User Agent

Introduction

userAgentData brand lists, so you can read the identity string and hint objects websites historically used for sniffing without installing spoof extensions just to see defaults. Developers debugging legacy server sniffers, IT verifying managed browser bundles, educators teaching UA reduction, and support teams collecting copy-pasteable tokens for CDN tickets all benefit from a calm local-only view. DeviceHub will not pretend frozen major versions or reduced OS tokens are errors, modern Chromium, Firefox, Safari, and Edge deliberately limit passive fingerprint detail, and Client Hints remain incomplete even where implemented. Pair with Browser Information for structured engine summaries, Browser Features when capability beats sniffing, JavaScript Test for runtime syntax smoke, and Screen Resolution when layout context accompanies identity debates. Device Information under Hardware stays separate when the ticket is viewport geometry rather than UA text. CDN engineers comparing edge logs to live browser output use this page to reconcile reduced tokens with what script can still read. Security teams auditing outdated WAF rules paste current reduced strings beside legacy regex expectations to justify rule updates. Edge IE-mode tabs produce dual-engine confusion, capture UA inside the exact mode users enabled for legacy intranet apps. CDN vendors sometimes log Sec-CH-UA headers while JavaScript only exposes userAgentData, discrepancies between server logs and this page are a frequent training topic for junior support staff. Automated Lighthouse runs record UA differently from user sessions, do not mix lab UA with customer UA in one ticket thread. Marketing pixels that still parse full OS versions from reduced strings waste sprint time, paste this page beside log lines when retraining sniffer rules. Spoof extensions for mobile emulation appear in refreshed readings, toggle extensions and reload when fake-mobile bugs are suspected.

What this tool does

The page displays the raw user-agent string and structured Client Hints the browser chooses to expose to script, with copy guidance for support notes. It does not send custom UAs to third parties, forge hints, or compute bot scores. Explanatory copy covers UA reduction and why regexes demanding precise minor versions fail on current browsers. When userAgentData exists, brand arrays, mobile flags, and platform strings appear with notes that getHighEntropyValues may remain gated. Refresh shows changes after toggling spoof extensions. Optional formatting wraps long UA strings for readability without altering content. Hint sections explain which fields are low-entropy by default versus which require optional high-entropy calls that may still return empty. Headless automation defaults differ from interactive Chrome, label capture method in CDN dispute tickets. Reduced Android WebView tokens may omit model identifiers your analytics pipeline still expects, use Browser Features beside UA when planning server-side fallbacks. Automated Lighthouse runs record UA differently from user sessions, do not mix lab UA with customer UA in one ticket thread. Bot scoring vendors asking for “real browser UA” samples should receive tokens captured here during an interactive session, not curl defaults from servers. Legacy intranet apps in Edge IE-mode need UA captured inside that mode toggle, not from the outer Chromium shell alone.

When to use it

Use User Agent when a server log, CDN rule, WAF, or ancient sniffer is the dispute; when verifying a spoof extension actually changed the string; and when teaching why feature detection beats UA parsing. Prefer Browser Features for does this API exist. Prefer Browser Information for a wider dashboard. Prefer Cookie or Storage tests when the symptom is state persistence, not identity. Avoid treating Client Hints as a full restoration of 2015-era UA richness, they intentionally withhold fields. Use when mobile Request Desktop Site toggles shift tokens mid-session, capture before and after. Use when bot mitigation vendors ask for UA samples from real browsers rather than curl defaults. High-entropy hints are not auto-requested here to avoid extra prompts during read-only audits. Automated Lighthouse runs record UA differently from user sessions, do not mix lab UA with customer UA in one ticket thread. In-app WebViews for social apps append custom tokens, capture inside the WebView when crashes happen only there, not from desktop Chrome. Safari on iOS reduces model identifiers, plan analytics fallbacks using Client Hints where implemented rather than regex on model tokens.

How it works

userAgent is a DOMString supplied by the browser and subject to reduction policies that freeze or bucket tokens. userAgentData, where implemented, exposes brands, mobile boolean, and platform with optional getHighEntropyValues for additional hints that may prompt, refuse, or return empty depending on browser policy, DeviceHub lists what script can read without claiming every high-entropy field appears. Reading these values needs no microphone or camera grant; DeviceHub typed permissions remain none for this diagnostic even when hint APIs have their own browser rules. Secure HTTPS is standard sitewide. Server-side Client Hints headers Sec-CH-UA are not duplicated here, this page shows JavaScript-visible surfaces only. Automated Lighthouse runs record UA differently from user sessions, do not mix lab UA with customer UA in one ticket thread. getHighEntropyValues may exist yet refuse platformVersion, DeviceHub lists availability without auto-triggering extra prompts during read-only audits. Firefox ESR rollouts change reduced tokens mid-year, retest UA after ESR upgrades before blaming application middleware.

Step-by-step instructions

1. Open User Agent in the exact browser and profile that hits the failing site or CDN rule, including private windows if that is where the bug lives. Step 1 for user-agent: record browser version and OS build alongside smoke outcome.
2. Copy navigator.userAgent into notes when a vendor insists on the raw string, annotating reduced tokens as expected privacy behavior.
3. Inspect userAgentData and related hint fields when present; treat blank sections as normal under current policies, not as DeviceHub failure.
4. Open Browser Information alongside so structured engine fields accompany any sniffer debate in the same ticket.
5. If an extension spoofs UA, disable it temporarily, refresh, and confirm the string changed to isolate extension versus default behavior.
6. When hints and UA disagree with server logs, note whether the server reads request headers while this page shows JavaScript-visible hint objects, they are related but not identical.

Common problems

0 folklore fail on reduced UAs. Bots and real browsers can look similar by design. In-app WebViews append tokens that confuse home-grown parsers. Assuming Client Hints always restore full OS and version detail wastes escalation time. Parsing Windows 10 tokens on Windows 11 reduced strings misroutes fixes. Treating JavaScript userAgentData as identical to Sec-CH-UA request headers confuses backend versus frontend teams. Automated Lighthouse runs record UA differently from user sessions, do not mix lab UA with customer UA in one ticket thread. Frozen Chrome major versions under UA reduction still update security patches, train support that “version looks old” is not always an outdated install. Automated Lighthouse lab UAs differ from customer interactive UAs, never mix both in one escalation thread without labeling source.

Privacy explanation

The UA string is already available to sites you visit; DeviceHub shows it locally without uploading it for ad profiling on this check. No extra device permissions are requested. Closing the tab clears the on-page view. Be mindful when pasting full strings into public trackers if policy requires redaction. Hint objects may include coarse platform data, handle according to your org data classification policies. Automated Lighthouse runs record UA differently from user sessions, do not mix lab UA with customer UA in one ticket thread. userAgentData in script requires backend logging, this page covers script-visible half only. WAF regex maintenance should attach current reduced strings from this tool when retiring rules written for 2015-era tokens. Comparing Sec-CH-UA request headers on servers to navigator.userAgentData in script requires backend logging, this page covers script-visible half only.