Device diagnostics
Test your device.
Find what's wrong.
Run a browser-based test, use the result as evidence, and follow the next step. DeviceOK also gives source-backed answers when the exact model or accessory changes the diagnosis.
What do you need to do?
Choose the closest starting point. You do not need to know the cause first.
Diagnose a problemStart with the symptom and narrow the cause from test evidence.→Run a device testCheck microphones, cameras, keyboards, displays, audio and more.→Find your modelSee verified ports, limits, compatible accessories and model-specific fixes.→Check compatibilityGet an exact answer for chargers, cables, displays, docks and supplies.→Look up an errorMatch a code or message to the safest next action before replacing parts.→Inspect a used deviceRun a repeatable check and keep a shareable report.→
Popular tests
Quick checks for the hardware people test most often.
Microphone TestCheck whether your browser can detect your microphone and receive live audio.→Webcam TestOpen your webcam locally to verify that the browser can access and display a live camera stream.→Keyboard TestPress keys and verify that the browser receives the expected keyboard events.→Mouse Button TestVerify left, right, middle, and extra mouse button events.→Gamepad Controller TestTest browser-detected controller buttons and analog axes.→Dead Pixel TestShow solid colors full-screen so you can visually inspect for dead or stuck pixels.→
Common problems
Start from the symptom instead of guessing the failed part.
Microphone Detected but No Soundthe microphone is listed but no audio signal is received→Webcam Shows a Black Screenthe camera opens but the preview remains black→Keyboard Typing Twiceone press produces duplicate characters→Mouse Double Clicking by Itselfone click is sometimes registered twice→Controller Stick Driftan analog stick moves while physically centered→Printer Has Lines, Streaks or Bandingprinted pages show repeated horizontal/vertical lines, gaps or streaks→
Exact compatibility answers
Model-specific limits and requirements, verified against primary sources.
YesWhat charger does iPhone 16 need, and how fast can it charge?iPhone 16 charges through USB-C. Apple states that fast charging can reach about 50% in around 30 minutes with a 20W-or-higher USB-C power adapter and USB-C cable. Apple also specifies MagSafe and Qi2 wireless charging up to 25W when the required higher-power adapter and compatible charger are used.→It dependsCan iPhone 16 connect to a monitor over USB-C?Yes, when the display path supports the required video mode. Apple lists DisplayPort support on the iPhone 16 USB-C connector and specifies native DisplayPort video output over USB-C for video mirroring and video out. The same USB-C port is limited to USB 2 data rates, so video capability should not be confused with high-speed USB data capability.→YesHow many external displays can a MacBook Air with M4 use?Apple states that MacBook Air models with the M4 chip support up to two external displays simultaneously in addition to the built-in display, subject to the supported resolution and refresh-rate combinations. Closing the lid does not increase that number on M4 MacBook Air models.→YesCan the 15-inch M4 MacBook Air use a 70W USB-C charger?Yes. Apple lists the 15-inch MacBook Air (M4, 2025) as fast-charge capable with a 70W USB-C power adapter. Apple also lists MagSafe 3 and two Thunderbolt 4 (USB-C) ports that support charging.→
Browse by device
Open a device family for relevant tests, failure paths and inspection guidance.
How DeviceOK works
A simple evidence-first loop. No fake hardware certainty.
1Run the useful test
Measure what the browser can actually observe.
2Read the result
Separate what passed, what failed and what remains unknown.
3Fix and retest
Follow the next evidence-led action, then verify the change.
167 live tools110 verified models64 exact compatibility answers31 guided checks