There are dozens of ways to wirelessly share files, from attaching them to an email to uploading them to social media. But not all of your options are equally secure. In fact, to keep prying eyes away from your data, we recommend that you send your files through a direct device-to-device connection.

Your phone and computer both come equipped with wireless transfer protocols that let you share files securely, sometimes without even revealing your phone number or email address. Each operating system—iOS, macOS, Android, and Windows—offers its own method, and once you know how each one works, you’ll be able to pick the best option for the devices you have.

Share files on iOS and macOS

Your iPhone, iPad, and Apple computer can all connect directly to other Apple devices via AirDrop. This type of link enables Apple devices to send files to each other, relying on Bluetooth to establish the connection and Wi-Fi to handle the data transfer. A key note: For AirDrop to function, you must enable both Bluetooth and Wi-Fi, but you don’t need to connect to an actual Wi-Fi network.

This method of sharing is anonymous, which means you can send a file without knowing the recipient’s email address or phone number—and without disclosing your own contact information to them. The downside is that it only works when you’re sending a file between two Apple devices, so you can’t use it on Windows or Android.

Apple hardware enables AirDrop by default, but you can always double-check. First, turn on your Bluetooth and Wi-Fi connections. Then, on macOS, open Finder and look for AirDrop in the column on the left. You should see a discovery option at the bottom of the window. For increased privacy, set it to Contacts Only, and for broader sharing, set it to Everyone. On iOS and iPadOS, open Settings and choose General, then AirDrop, and, again, select either Contacts Only or Everyone.

Once you’ve enabled AirDrop, you can start sending data. Whenever you see the Share button on your Mac, iPhone, or iPad (it looks like a box with an arrow pointing up out of it), you can click or tap that button and choose AirDrop from the menu. The system will detect any other AirDrop-enabled device within about 30 feet. When the phone or computer you’d like to share with appears in the AirDrop window, tap on it to start the transfer.

This works for photos, webpages, documents, and plenty more. Before accessing the file, though, the recipient needs to approve the share. This is important because some people abuse the anonymity we mentioned earlier, using it to send obscene or obnoxious files to strangers. To prevent this from happening to you, either refuse to accept files when you don’t know the recipient, or make sure to set your AirDrop discovery to Contacts Only.

What if you want to send a file to a friend’s Android or Windows device? When you hit that Share button, you can pick a different option—such as an email or a file-syncing app like Dropbox—from the pop-up menu. However, these file-sharing methods require that you have the recipient’s contact information and that your phone or computer is connected to the internet.

Let’s say you use Dropbox on your iPhone, for example. Choose a file you’d like to send to a friend, tap Share, and pick Dropbox from the menu. Next, choose a folder in your Dropbox, and the file will upload to that location. Finally, provide your friend’s email address, and they will receive an email containing a link that they must click to download the file. This process is not quite as simple as AirDrop, but it will still get the job done.

Share files on Android

Android has had several AirDrop-like options through the years, and the latest is called Nearby Share. Find it on devices running Android 6 or later by entering Settings, then navigating to Google, Device connections, and Nearby Share. It should be on by default, but you can also enable it manually. Once it’s on, you’ll see Nearby Share as an option whenever you tap the Share button on your device (on Android, this button looks like a “less-than” sign).

To set who can share files with you, select Device visibility from the Nearby Share menu. The options are All contacts (people in your contacts can see your device while its screen is on and unlocked), Some contacts (the same, but only for contacts you pick), and Hidden (your device is only visible while Nearby Share is actually open).

For Nearby Share to work, both the sender and recipient must have Nearby Share enabled, and the devices need to be held close together. The option to either Accept or Decline the share is always available to the recipient, so you can’t be forced to accept the transfer of something you don’t want or expect.

Google says Nearby Share uses the best available protocol to transfer the file, choosing from Bluetooth, Bluetooth Low Energy, WebRTC, or peer-to-peer Wi-Fi, so the devices themselves don’t actually have to be online for the transfer to work—they are moving the files directly, device to device, without relying on another network.

When you tap that Share button in Android, other options will present themselves too. One of these is Bluetooth, which can transfer data quickly, device to device, potentially even if they’re several hundred feet apart. If you can’t use Nearby Share for whatever reason, Bluetooth is a useful alternative.

To enable Bluetooth, enter Android Settings, go to Connected devices, and toggle Bluetooth on. Once it’s enabled, the Bluetooth icon will appear any time you want to share something. Tap it, and Android will list any nearby Bluetooth-enabled devices—both Android and Windows—to which you can send that website or file. The receiving device may have to confirm the pairing action, but after that, the file will transfer easily.

As on iOS, there are a variety of other apps ready and willing to help you get a file from one phone to another. These probably include Gmail, Google Drive, OneDrive, Twitter, and Dropbox, depending on what you have installed on your phone. Using these apps won’t send files directly between devices though, and you’ll need to be connected to Wi-Fi or a cellular network for them to work.

Share files on Windows

For Windows devices, direct transfers are best done over a Bluetooth connection. Although you can share Windows data over Bluetooth with Windows and Android devices, Apple machines won’t accept a Bluetooth file transfer. If you want to make a Windows-to-Windows connection, you can use Near Share, which works much like Apple’s AirDrop.

First, enable Bluetooth. On a Windows 10 machine, open the Start menu, click the cog icon to launch the main settings pane, then choose Devices, Bluetooth & other devices, and switch Bluetooth on.

To actually share the file, you’ll have to connect the sending device to the receiving one. From the same Bluetooth & other devices screen, hit Add Bluetooth or other device, then select Bluetooth to search for another Bluetooth-enabled Windows or Android machine. When the device you’re looking for appears, tap or click it to connect.

Now that your devices are successfully talking to each other, stay on the Bluetooth & other devices page and click Send or receive files via Bluetooth below the list of devices. Choose Send files, then the device you want to beam them to, and hit Next. On the subsequent screen, click Browse to search through your files, tap the one you want, and select Next once more to confirm.

Beyond Bluetooth, Windows has another method for moving your files wireless between two Microsoft devices, imaginatively called… Nearby Sharing. Like AirDrop, it combines Bluetooth and Wi-Fi to let you share files even without a web connection. To enable it, go to Settings, then System and Shared Experiences (this needs to be turned on for both of the Windows computers you’re using).

When you’re ready to share a file, select it in File Explorer, then open the Share tab on the ribbon menu at the top. Click the Share button, and a dialog box full of options will open up, including a list of apps you can use to transfer the file to someone else. Select the other computer when it appears, and you can complete the transfer.

While a direct device-to-device transfer protocol that works between Apple, Microsoft, and Google devices would be welcome, it doesn’t look as though something like that will appear anytime soon. In the meantime, the best method for you depends on which devices and platforms are involved.