Browser Info

About Browser Info

Every modern browser exposes a surprising amount of information about itself and the device it is running on — some through the legacy user agent string, some through dedicated JavaScript APIs. Web developers use this information to serve the right experience to each visitor, detect bugs specific to certain browsers, and know which features they can safely rely on.

This tool gathers everything a website can see about your browser and device, in one place.

What is a user agent?

A user agent is a short string your browser sends with every HTTP request. It traditionally contains the browser name and version, the rendering engine, and the operating system. Modern browsers have reduced what it reveals to protect privacy, but it is still a first line of detection for many sites.

A user agent typically looks like this:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Breaking it down:

The "Mozilla/5.0" prefix is purely historical. In the 1990s, browsers that did not claim to be Mozilla were served inferior versions of sites, so Internet Explorer, Chrome, Safari and Edge all adopted the Mozilla prefix — a decision that has never been corrected.

The four major rendering engines

Modern Edge uses Blink despite its historical link to Trident — the engine was swapped in 2020. This is why detection based on user agent alone is unreliable and feature detection is preferred.

Feature detection over browser detection

The modern best practice is not to detect the browser, but to detect whether the feature you need is supported. This is more robust because it works for future browsers, avoids false negatives in niche browsers, and does not require updating when browser versions change.

The feature matrix on this page tests dozens of common APIs across categories:

• Core web APIs — Fetch, Promises, async/await, Intersection Observer
• Graphics — Canvas 2D, WebGL, WebGL2, WebGPU
• Storage — LocalStorage, IndexedDB, Service Workers, Cache API
• Media — Web Audio, MediaRecorder, WebRTC, Web Speech
• Hardware — Geolocation, Bluetooth, USB, Gamepad, Vibration
• CSS — Grid, Flexbox, Custom Properties, Container Queries

Client Hints: the modern replacement

Browser vendors are gradually moving away from the monolithic user agent string toward Client Hints. Instead of sending everything on every request, the browser sends small, specific pieces of information only when the server asks for them:

Chrome, Edge and Opera support Client Hints. Firefox and Safari do not — they continue to rely on the traditional user agent, though they have also started reducing the version information in the UA to protect privacy.

Hardware and device APIs

Several APIs reveal hardware information, though with privacy-preserving imprecision:

• navigator.hardwareConcurrency — logical CPU cores (usually accurate).
• navigator.deviceMemory — approximate RAM in GB, rounded down to a power of two and capped at 8 (Chrome only).
• navigator.maxTouchPoints — maximum simultaneous touch points the device can track.
• navigator.connection — effective connection type (4G, 3G), downlink speed and RTT (Chrome only).

These are intentionally coarse to limit fingerprinting: two devices with different amounts of RAM may report the same value.

Common use cases

Privacy

This browser info tool runs entirely in your browser. All detection is performed locally using standard JavaScript APIs. The results are not transmitted, stored or logged on any server. You can safely use it to audit your own browser's fingerprint.

Frequently Asked Questions

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