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Used phone test apps and laptop test software: what to use

Updated September 28, 2026

Test your device now in the browser, free, no app needed.

Search for a "used phone test app" or "laptop test software" and you get dozens of names. No single tool checks everything: some things only the device's own Settings can tell you, some need a computer and a cable, and most of the faults you would actually notice (screen, touch, speakers, cameras) can be tested right in the browser. This guide sorts out which tool does what, so you can check a device in about 15 minutes without installing anything on someone else's phone.

Tip: if you are meeting a seller with their phone, open soimay.com on that phone first. No app, no sign-in, and sellers are far more likely to agree to it.

1. Three kinds of tools, three different jobs

  • Browser-based tests (like Soi Máy): check what you can see, hear and touch: dead pixels, touch, speakers, microphone, cameras, sensors, keyboard, touchpad. They work on phones, tablets, laptops and desktop PCs.
  • Installed apps (TestM, Phone Doctor Plus, the maker's own diagnostics): also test hardware and read a few extra details, but you have to install them and grant lots of permissions. Depending on the app, there are ads or a paid tier.
  • Computer software (3uTools for iPhone, CrystalDiskInfo for laptop drives): reads deeper, such as replaced parts, battery cycles and SSD health. It can't tell you whether a speaker crackles or part of the touch screen is dead.

None of them can check an iCloud or Google account lock for you. That has to be checked in the device's Settings.

2. What only Settings can tell you

Do these first, because they decide whether the deal goes ahead:

  • iPhone, iPad: the top line of Settings should be empty and Find My iPhone should be off. Battery is under Settings › Battery › Battery Health. From iOS 15.2, replaced parts are listed under Settings › General › About › Parts and Service History.
  • Android: make sure the Google account has been removed. Samsung has the *#0*# test menu and Samsung Members › Diagnostics; many other brands have diagnostics in their support app.
  • IMEI: dial *#06# and compare it with the IMEI in Settings and on the box.

Step by step: buying a used iPhone, buying a used Android phone, and the self-check list in the checklist.

3. Test the hardware in the browser

Open soimay.com on the device you are checking (Safari on iPhone, Chrome on Android and computers), tap Start testing and work through the tests. The ones that matter most:

Dead pixel, backlight bleed and burn-in testFind dead or stuck pixels, backlight bleed, burn-in and lines on a phone or laptop screen. Eight full-screen colours, free, no app to install. Touch screen test: dead zones and ghost touchesSwipe to fill a grid of cells and spot dead touch zones or ghost touches on a phone or tablet. Runs full screen, free.
  • Speakers and microphone: the speaker test plays left and right separately; the microphone test records a clip and plays it back.
  • Cameras: the camera test opens each camera so you can check focus, dust and haze.
  • Face ID, fingerprint: the biometrics test.
  • Sensors and vibration: the sensor test covers the gyroscope, auto-rotate and the vibration motor.

4. Laptops and desktop PCs

On a computer, choose Laptop/PC in Soi Máy and run the keyboard, touchpad and mouse, screen, speaker, microphone and webcam tests, plus the CPU test to see whether the machine overheats and slows down. Two checks need extra software:

  • Windows laptop battery: run powercfg /batteryreport in Command Prompt, nothing to install.
  • Drive health: the portable version of CrystalDiskInfo, then look at Health Status.

How to read each number: checking a used laptop and buying a used MacBook.

5. When to add 3uTools

For an expensive used iPhone, plug it into 3uTools to see the parts report and battery cycle count. It adds to the browser tests rather than replacing them: a report that says "Normal" can still hide a dead pixel or a crackling speaker. How to do both in one go: checking a used iPhone with 3uTools.

When you're done

On the Results page, save a PDF or create a link and QR code. A seller can send it to a buyer who is far away, and a buyer can keep it to compare against if something goes wrong during the warranty period.

Check your whole deviceScreen, touch, speakers, microphone, cameras, battery and more, right in the browser. Free, with a PDF report and a QR code to share.

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