Bought a second-hand phone? Check what came with it
A used phone is a good deal until you wonder what is still on it. The previous owner's apps, their Google Account, a setting that lets another app read the screen. This page shows how to make the phone yours: reset it, then check it with Applore's free Suspicious App Checker and Safety Check.
Short answer
What a used phone can carry
A phone that was not reset keeps whatever its last owner left on it:
- Apps, including ones with no icon in the app list.
- Special access that an app was granted: accessibility (reads the screen), notification access (reads messages as they arrive), device admin (hard to uninstall).
- Accounts that are still signed in, and the Google Account’s own sharing settings, such as location sharing in Maps.
- A keyboard you did not choose. A keyboard sees everything you type.
- Developer options and USB debugging, which let a connected computer do more than usual.
Most used phones carry nothing worse than clutter. The point of checking is to know, not to assume either way.
Step 1: reset the phone
- Check that the previous owner has removed their Google Account: Settings › Accounts (or Passwords & accounts) should show none of theirs. Android’s factory reset protection can lock a phone to the previous account after a reset. [1]
- Back up anything of yours that is already on the phone. A factory reset erases everything on the phone and cannot be undone.
- Reset: on most phones Settings › System › Reset options › Erase all data (factory reset). Menu names vary by phone maker.
- Set the phone up with your own Google Account and a new PIN or password. Choose your own keyboard when asked.
Step 2: check it with Applore
- Install Applore from Google Play (Android 8.0 and up). Allow the consent screen that explains what the check reads.
- On the Home screen, open the Suspicious App Checker. It compares every installed app with a reviewed, signed list of known stalkerware and harmful apps built from public research [2], shows what Google Play Protect reports if it is on, and flags apps with warning signs: installed from outside an app store, hidden icon, accessibility, notification or device admin access, or a copy of a popular app without the real publisher’s signature.
- Read each flagged app. About this app explains why it was flagged and where it came from. Apps installed by the phone maker’s firmware are treated like store installs, so a normal phone shows few or none.
- Open Safety Check and go through the list. It opens each settings screen for you: accessibility services, notification access, device admin apps, and your Google Account’s signed-in devices, third-party access, Maps location sharing, Family Link, Photos partner sharing and Gmail forwarding. Mark each item as checked.
- Optional, Pro: open Phone back check and save a snapshot now. The next time the phone leaves your hands, you can compare and see what changed.
Each flagged app gets a level: Known monitoring app High Worth a look Not flagged. The levels describe how strong the signs are, not what the app has done.
Step 3: make it yours
- Run the free Hardware Test in Device Information to check the speakers, sensors, vibration and buttons, especially if the return window is still open. How to test a phone’s hardware.
- Turn on App Lock for banking, messages and photos, so a phone that leaves your hands again gives up less. App Lock.
- Keep Applore installed. It checks again when apps are added or changed and once a day, and reminds you if something serious appears.
Common problems
The phone asks for the previous owner’s account after the reset
That is factory reset protection. Only the previous owner can clear it. [1] Go back to the seller; do not buy a phone that stays locked to someone else’s account.
I cannot reset the phone yet
Run the Suspicious App Checker and Safety Check first, and do not sign in to your own accounts until you have. Treat anything with a hidden icon and accessibility or notification access that you do not recognise as a reason to insist on the reset.
The check found nothing. Is the phone clean?
A Not flagged result means no match with the known list and not enough warning signs. It is a good sign, not proof. The reset, your own account and a new screen lock are what make the phone yours.
What stays private
The check runs on the phone. The threat list is downloaded and compared on the device; findings, your trust list and any snapshot stay there. The list of installed apps is not sent to analytics or advertisers. Hardware Test results are stored on the phone. Data and privacy.
Next steps
- Buying rather than bought? Use the checklist before you buy.
- Read how to check an Android phone for spyware and stalkerware for the manual checks, and how detection works for every signal and level.
- See what Applore will and won’t do.
Questions
If I factory reset the phone, do I still need to check it?
A factory reset removes the previous owner's apps, accounts and settings, so it is the single most useful step, and it cannot be undone. A check afterwards is still worth two minutes: it shows what is installed after the reset, including any apps the phone maker or carrier preinstalled, and gives you a first result to compare against later. If you cannot reset, for example because the seller's account is still on it, the check matters more.
Applore flagged an app that came with the phone. What now?
Read what Applore says about it first. Apps installed by the phone maker's own firmware are treated like app-store installs, so most are not flagged. A flagged preinstalled app is usually a region or carrier app with broad access. If the explanation makes sense and you recognise the app, you can mark it as trusted. If it has a hidden icon and accessibility or notification access and you do not know it, treat it as worth removing after the reset.
Is the used-phone check free?
Yes. The Suspicious App Checker, Safety Check and the hardware tests are free in Applore Free and Applore Pro, and the safety screens show no ads. Applore Pro adds Phone back check, which saves a snapshot of the phone's apps and settings so you can see later what changed, and removes ads elsewhere in the app. Compare Free and Pro.
What can the check miss on a used phone?
Anything outside the apps it can see: changes to the phone's system software, tools that need a rooted phone, apps in a work profile or Private Space, and spying through an account that is still signed in somewhere else. A Not flagged result does not prove the phone is clean. A factory reset, a new screen lock and your own Google Account cover most of what a check cannot. How detection works.
Sources
- Help prevent others from using your device without permission, Android Help. Checked 2026-10-09.
- Stalkerware indicators, Echap (CC BY 4.0). Checked 2026-10-09.
Next steps
Check your used phone with Applore, free
Manage apps and files, lock private apps, and check for known stalkerware.