Both WhatsApp and LINE let you make and receive free calls on your mobile phone. These services are among the most popular instant messaging apps. But which one is best for saving money on calls and for a clear connection? When testing both apps, we looked at criteria such as popularity, cost and features.

The two apps offer similar features. And both apps are free to download, offer free voice and video calling, and allow free file and location sharing. Ultimately, your choice may come down to which one your friends and family use, and which interface you find easiest and most pleasant to use.

The number of people using an app is an important factor in the decision to use it. Calls are free between users of the same network. So the more friends and correspondents you have on one app, the more opportunities you have to make free VoIP and video calls.

WhatsApp is the clear winner here, as it has the largest user base worldwide. While WhatsApp is popular worldwide, Japan-based LINE's popularity is concentrated in a few countries in Asia.