Many of us were rather uncomfortable when Facebook bought WhatsApp; the social networking giant doesn't exactly have a great reputation for privacy. Since then, however, WhatsApp has added end-to-end encryption, which is very secure.

Still, if you know everything there is to know about WhatsApp and you'd rather use something other than WhatsApp, there are a lot of great options out there.

Wickr

A self-destructing message app, Wickr transfers control of mobile messaging from the receiver to the sender. This means that you get to decide how long your message sticks around. Before you send it, you can choose a self-destruct time ranging from a few seconds to more than five days. Once the timer runs out, your message will be erased from the recipient's phone.

The user interface is quite simple. When you open a new message, just tap the lock icon to start the self-destruct timer. Each message has a live countdown so you know how long you have until it disappears. Your messages can contain text, images, video, audio, or attached files. Wickr includes convenient integration with Box, Dropbox, and Google Drive, so you can send files directly from your cloud storage.

Wickr searches your contacts for people you know that also use the app and automatically adds them to your contacts list. However, you can open a Wickr account without a phone number or e-mail address, and one of your contacts hasn't added this information, you'll have to add them by their username.

The app offers 4,096-bit RSA encryption, an extremely secure protocol. This actually exceeds the NSA Suite B Compliancy guidelines, meaning it's compliant with top-secret communication guidelines. It also deletes all all meta-data from your messages, like date, time, location, and device information.

Even with this level of security, messages are encrypted and sent quickly—in my testing, it only took a few seconds to encrypt a text message with a 2MB photo, and it was delivered just as fast.

Download Wickr for iOS (free)

Download Wickr for Android (free)

Signal

With endorsements from Edward Snowden, Laura Poitras, and Bruce Schneier, you can absolutely trust Signal to safeguard your privacy. And the app itself couldn't be simpler. You can send messages that include all sorts of files and even make encrypted calls. All for free.

The fact that you don't need another username is a big bonus for usability. Just sign up with your phone number, and you're set to go. Open Whisper Systems, the creators of Signal, don't have access to any of your messages or your encrypted calls, ensuring total security.

It's hard to beat Signal for ease of use. It's a dead simple app that anyone who's ever sent a text message will be able to use. It's totally free, and highly secure. There's really no downside.

Download Signal for iOS (free)

Download Signal for Android (free)

Threema

One of the cool features of Threema is that you can send your location -- tap on the "attach" button and you'll send a geographic marker to your recipient. Once they receive it, they can just tap on it to get your location on a map. This is great when you're trying to meet up with someone or describe where you are.

Threema isn't free, but at $2.99 it's still very affordable, and there's no subscription fee. There are no plans to introduce ads or start charging for use, so you don't have to worry about the app changing once you buy it.

Threema provides true end-to-end encryption; your message is encrypted right on your device, and only the receiver's device can decrypt it. The decryption key can't be accessed by the company's servers. Threema uses Elliptical Curve Cryptography, which is equivalent to 2048-bit RSA encryption. For further security, you don't have to link your phone number, e-mail address or anything else to the app. You can also add a PIN lock to the app. Even if someone gets into your phone, they'll still have to get past that to get to your messages.

Another cool feature is an indicator of how sure you can be that the person who sent you a message is really that person. If you add a contact by entering their username, that contact will have a red verification level. If Threema syncs with your contacts and pulls a username from its servers using SMS or e-mail validation, that contact will get an orange verification. To get to the green verification level, you'll have to exchange keys with them by scanning the QR code on their device.

Messaging on Threema is quite fast; simple text messages are sent in a matter of seconds. During testing, it took about 30 seconds to upload, encrypt, and send a 3.9-MB photo from Dropbox.

Download Threema for iOS ($2.99)

Download Threema for Android ($2.99)

Telegram

Telegram is a great free secure messaging app. offers support for text, photos, videos, audio, and documents. You can set a timer for your message to self-destruct, erasing it from the receiving device, but this is optional. Like Threema, Telegram looks like a text-messaging client with read receipts. You have the option of changing the message background to inject some variety into your messaging, as well.

Because the group behind Telegram is a non-profit organization, the app costs nothing and is ad-free. Their website says that they're  "building a messenger for the people," and that if the group runs out of money, they'll add a link to the app for donations or create some non-essential paid options. You can also get desktop clients for Telegram, which is very convenient.

Telegram's encryption is "based on 256-bit symmetric AES encryption, 2048-bit RSA encryption, and Diffie–Hellman secure key exchange." The method of encryption, was created specifically for this project, and is open-source. Telegram offers the ability to start "secret chats," which use full end-to-end encryption, aren't stored on the Telegram servers, and self-destruct after a set time for sending extra-secure data.

This encryption doesn't slow down the sending of messages, though—when testing the app, messages that I sent were transmitted almost instantly, making it a great IM-like client. Uploading and transmitting a 1.5-MB document took a bit longer.

Download Telegram for iOS (free)

Download Telegram for Android (Free)

Which is best for you?

All four of these apps are great options for replacing WhatsApp if you're worried about information privacy. The organizations behind them are committed to security, they offer high-grade encryption, and you maintain full control over who sees your information.

If all of these apps sound good to you, I'd recommend going with Telegram. It has a large number of users, and the ability to send messages from your desktop is really fantastic.

What do you think? Does Facebook's acquisition of WhatsApp make you nervous about data privacy? Will you be switching to another messaging app?

Photo credit: she spy by Kangrex via Flickr