How do I find the exact screen resolution a user is running?

The Screen Size Checker reports window.innerWidth and window.innerHeight (viewport size) as well as screen.width and screen.height (physical screen dimensions) and window.devicePixelRatio (for HiDPI/Retina displays).

What is the device pixel ratio and why does it matter?

The device pixel ratio (DPR) is the ratio of physical screen pixels to CSS pixels. On Retina displays, DPR is 2 or 3, meaning one CSS pixel maps to 4 or 9 physical pixels. This affects how images and borders appear and is critical for testing responsive images.

Can I see what browser APIs are supported?

Yes. The Browser Info tool reports support for key browser APIs including Web Crypto, Service Workers, WebGL, WebAssembly, and Bluetooth, helping you diagnose compatibility issues.

Inspect Browser & Device Information

Understanding exactly what browser, operating system, screen resolution, and hardware a user is running is essential for reproducing reported bugs, testing responsive layouts, and verifying that your application behaves correctly across different environments. devtoolkit.sh's browser inspection tools surface this information instantly from your current browser session. The Screen Size Checker reports the current viewport dimensions and device pixel ratio — the numbers you need to verify responsive breakpoints and debug layout issues on high-DPI displays. The Device Info Viewer shows the operating system, platform, hardware concurrency (CPU thread count), and device memory if available. The Browser Info tool provides a detailed breakdown of the user agent string, the detected browser name and version, supported APIs, and relevant feature flags. Together, these tools let you capture an accurate snapshot of any browser environment — invaluable when a user reports a bug and you need to match their exact setup to reproduce it.

SCRScreen Size Checker

View window size, screen resolution, pixel ratio, and active breakpoint in real time.

DEVDevice Info Viewer

Display navigator properties: user agent, platform, language, hardware concurrency, and more.

BRWBrowser Info

Detect browser name, version, OS, and check support for key web APIs.

FAQ

How do I find the exact screen resolution a user is running?: The Screen Size Checker reports window.innerWidth and window.innerHeight (viewport size) as well as screen.width and screen.height (physical screen dimensions) and window.devicePixelRatio (for HiDPI/Retina displays).
What is the device pixel ratio and why does it matter?: The device pixel ratio (DPR) is the ratio of physical screen pixels to CSS pixels. On Retina displays, DPR is 2 or 3, meaning one CSS pixel maps to 4 or 9 physical pixels. This affects how images and borders appear and is critical for testing responsive images.
Can I see what browser APIs are supported?: Yes. The Browser Info tool reports support for key browser APIs including Web Crypto, Service Workers, WebGL, WebAssembly, and Bluetooth, helping you diagnose compatibility issues.