Updated Feb 2013 (Reviewed the newest versions and added review of the iPhone apps).
Update 2 (Feb 2014): As you probably know by now, Whatsapp got acquired by Facebook recently. Hopefully we will see some good things coming out of this deal, especially considering my concerns with Whatsapp and the lack of a single identity other than a phone number. And if you are interested in startups, consider signing up for Startup Letters.
Viber and WhatsApp are both apps that aim to provide free communication between you and other smart phone users, without the hassle of manually adding contacts. This is achieved by identifying the users based on their phone number, so everyone in your phonebook that is already using the service will automaticly show up in the list of people you can contact for free!
First a short summary of the features of the two apps.
Viber
- Supports iOS, Android, Blackberry, Nokia/Symbian, and Windows Phone
- Free
- Voip calling
- Text chat
- Group chat
- Location sharing
- Picture sharing
- Message popups (Android only)
- Supports iOS, Android, Blackberry, Nokia/Symbian, and Windows Phone
- $0.99 (iOS), free 7 month trial, then $0.99 pr year (Android)
- Text chat
- Group chat
- Status messages
- Voice messages
- Broadcast messages
- File transfers/MMS (images, video and audio)
- Sharing location
Comparison
iPhone
On the iPhone the Viber interface works really well, and I like that the app can be used as a decent replacement for the original phone app. The design of both iPhone apps are pretty ordinary, and they are easy to navigate. Some might think that the Viber app is a bit bloated if they don't want to use it as a replacement for the standard phone app. Whatsapp is a bit more lightweight and runs a tad more smoothly.
I don't use my iPhone on a daily basis (I prefer my Galaxy Nexus), so I cannot really tell how the apps work over longer periods of time, such as which one drains the most battery and so on. In the short period I've used them, both have performed equally well. Messages appear near instantly (I've only tested on HSDPA and Wifi connections), and I haven't encountered any bugs yet.
Android
In a nutshell, the Android version of Viber is a very close port of the iPhone app, something I'm definitely not a fan of. The Whatsapp app is more tailored for Android, removing features that's unnecessary on the platform, making it extremely lightweight. For instance, the Viber app still looks like the version of the iPhone contacts app, including dialer, full contact list and so on. This makes it seem very bloated, and it's not as intuitive for an Android user to find his/hers way around. What makes sense on iOS doesn't necessarily make sense on Android. I wish they rather did like Whatsapp and integrated with the standard Android contacts (so you have the option to call, text or Whatsapp a contact directly from the stock Android contacts app). They did this previously, and I wish they would reintroduce this feature.
Let me demonstrate that point with a short example. I want to contact my friend Anders (using my Galaxy Nexus), so I open up the normal contact card. If he's online on Google Talk, I'll probably shoot him a message there. If not I am presented with a lot of different ways to contact him, either by text, calling, Google+, LinkedIn, Whatsapp and so on. I won't open up Viber just to see if he has an account there as well.
In the past I've also had more issues with Viber than Whatsapp on Android, but both apps seem pretty stable now.
The threat of Facebook Messenger
It's been almost two years since I first reviewed Viber and Whatsapp. A lot has happened since then, and perhaps the most important for Viber and Whatsapp is the introduction of Facebook Messenger. By now it has grown into a quite reliable app, running in the background with a very low footprint. It now also features delivery reports, which make it a good alternative to both Viber and Whatsapp for texting purposes. If it introduces voice and maybe video chat I think it will be the messaging app of choice for a lot of people, probably me included.
What Facebook Messenger doesn't do is importing the contact list from your phone. But frankly it doesn't need to. I have about 700 contacts on Facebook not using either Whatsapp or Viber, but probably just a handful Viber/Whatsapp contacts that I don't have on Facebook. And I probably never communicate with them anyway.
Actually, the thing I dislike the most with both Viber and Whatsapp is the fact that you can only use it on one device per phone number. During the last few years I've been living in many different countries, and the friends I made in the different countries have different phone numbers on me. That means I would have to carry 6 phones with me if I wanted everyone to be able to reach me on Viber/Whatsapp. As I can text my Danish friends for free anyhow I decided to set up my main phone with my Norwegian number. That means only people that have my Norwegian number in their address list can reach me on those services. That's obviously not an issue with Facebook messenger.
I think Whatsapp and Viber could fix this issue (and stay competitive in the future) by making users able to "link" different phone numbers, so that no matter which of my numbers someone has on file, they will only see one listing of me in Whatsapp/Viber, and I would get messages they send me on whichever device I am currently using. They could also offer a closer integration with Facebook, linking your Facebook profile ID with your account and storing the profile IDs of all your friends. This way you would get all Facebook friends that also use Viber/Whatsapp (and link it with their FB account) in your contact list as well.
Concluding thoughts
Currently around 160 of my friends use WhatsApp and around 150 use Viber, so it's quite even. Most of my friends that's on one service also use the other. This might vary across regions though.
Personally I find that Whatsapp works best for messaging, so I only use Viber for calling. After changing my cell phone operator last fall, I have free calls to all the countries I call regularly. Therefore I haven't used Viber at all the last six months. I still have to pay for international texting, so Whatsapp is still relevant.
To sum it up: I prefer Whatsapp for texting, especially on Android which is my preferred mobile OS. Viber is a bit bloated in some respects, but it's still worth installing. After all it's free, and it's the only of the two that supports calling. On iPhone Viber is a better choice, but if you don't want to use it as a replacement for the standard phone app you might find Whatsapp more suited for your needs. As mentioned, I fear that both apps might become less relevant if they don't make it easier to use the app on more devices/with multiple phone numbers and find more (Facebook) friends.
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