The short answer: On Windows, BitLocker To Go encrypts a whole USB drive with a password, but turning it on needs Windows Pro, Enterprise or Education. On a Mac, Control-click the drive in Finder and choose Encrypt: Apple converts the drive to APFS first, and without the password you can't get at the data. On either, a password-protected archive locks a few files, at the cost of extracting them to edit. ZapLock locks one folder on the drive where it is, leaves everything else readable, and opens it with your ZapQR sign-in on Mac, Windows and Android.
Three built-in ways, and where they stop
BitLocker To Go (Windows)
Encrypts the entire USB drive. You set a password and save a recovery key when you turn it on.
- Turning it on needs Windows Pro, Enterprise or Education
- Not available on Windows Home
- The whole drive, not one folder
Finder Encrypt (Mac)
Control-click the drive in Finder's sidebar and choose Encrypt. Apple converts it to APFS, then encrypts it.
- Apple: without the password you can't access the data
- Older Macs without APFS can't read it
- Windows doesn't read APFS out of the box
Password-protected archive
Zip the folder with a password (7-Zip with AES-256, or a Mac encrypted disk image) and keep the file on the drive.
- Extract to edit, then archive again
- Forget the password and it won't open
- Everyone who uses it needs the same password
Deleted isn't always gone on flash. When any tool replaces plain files with encrypted ones, the old blocks on a USB stick or SSD may not be wiped straight away. If the drive ever held something very sensitive unencrypted, lock it on a fresh drive, or erase the old one with the OS disk tool once the locked copy is safe.
One folder locked. The rest of the drive untouched.
USB DRIVE (exFAT)/
├── Photos/
├── Presentations/
└── HR files/
Anyone who plugs it in
reads everything.
USB DRIVE (exFAT)/ ├── Photos/ ├── Presentations/ └── HR files/ ← same name, same place ├── zaplock.json ├── recipients/ └── d/ (encrypted) The drive stays exFAT, so Mac and Windows still read the rest.
Each device that opens the folder needs its own key file on the drive. Plug the drive into a device that can already open the folder, with ZapLock running, and it adds your other signed-in devices.
How to lock a folder on a USB drive with ZapLock
On a Mac, a Windows PC or an Android phone. The drive can stay exFAT, so it keeps working on both Mac and Windows.
Install ZapLock and sign in
Get it from the Mac App Store, Microsoft Store or Google Play, and sign in with a free ZapQR account.
Sign in on a second device
Sign in on another phone or computer too. Each device holds its own share of a folder's key, so losing one doesn't lock you out.
Lock the folder
On a Mac, right-click the folder on the drive in Finder and choose Services → Protect with ZapLock. On Windows, right-click it in File Explorer and choose Protect with ZapQR. On Android, choose Add folder… and pick it on the USB drive.
Let your other devices in
With the drive still plugged in and ZapLock open, your other signed-in devices get their key files on the drive. Eject the drive properly before you unplug it.
Open it anywhere you're signed in
Plug the drive into any of your devices with ZapLock and unlock the folder with your sign-in, plus Touch ID, Windows Hello or your fingerprint if you've turned on the unlock check.
What ZapLock won't do
Worth knowing up front, so nothing surprises you later.
- You need a free ZapQR account. That sign-in is what replaces the password.
- Opening a folder needs a connection to our service, which releases its half of the key. A new unlock waits until you're back online.
- If a folder's key lives on only one device and you lose that device, the folder can't be opened. Sign in on a second device before you lock anything you can't lose.
- No Linux, and the apps aren't open source.
- Sync services keep version history. If plain copies were ever synced, your provider may still hold them.
USB drive lock FAQ
Can you put a password on a USB drive?
Yes, on the whole drive. Windows Pro, Enterprise and Education have BitLocker To Go, and a Mac can encrypt a drive from Finder, which converts it to APFS. Both lock the entire drive behind a password. To lock just one folder and leave the rest readable, use a password-protected archive or ZapLock.
How do I lock a USB drive on Windows 11 Home?
BitLocker To Go can't be turned on in Windows Home. On Home you can keep files in a password-protected 7-Zip archive on the drive, or lock a folder on the drive with ZapLock, which runs on Home and Pro and opens with your sign-in and Windows Hello.
Can I lock just one folder on a USB drive?
Not with BitLocker To Go or Finder's Encrypt: both encrypt the whole drive. ZapLock locks one folder where it is. The folder keeps its name, the rest of the drive stays readable, and the files inside are encrypted with AES-256-GCM.
Will the locked folder open on both Mac and Windows?
Yes, if the drive uses a format both read, such as exFAT, and ZapLock is installed and signed in on each computer. A device needs its own key file on the drive first: plug the drive into a device that can already open the folder, with ZapLock running, and it adds your other signed-in devices.
What happens if I lose the USB drive?
Whoever finds it sees the rest of the drive as normal and the locked folder as encrypted files they can't read without your sign-in. Your files are only as safe as your copies, though: a lost drive is lost data unless you keep a copy somewhere else.
What if I forget my BitLocker or Finder password?
With BitLocker To Go you need the recovery key you saved when you turned it on. Apple says that without the password you can't access the data on an encrypted Mac drive. ZapLock has no folder password to forget: you open folders by signing in.
Is there a free way to lock a folder on a USB drive?
Yes. ZapLock's Free plan locks one folder for good, and opening folders is always free. A password-protected 7-Zip archive is free too, if you don't mind extracting files to edit them. See pricing.
Lock your first folder in a minute.
Free for one folder, for good. On Mac, Windows, iPhone, iPad and Android.
Built-in options checked 25 October 2026 against: Microsoft: BitLocker Drive Encryption · Apple: Protect your Mac information with encryption.