The app lets one choose from servers in five locations: the US, Canada, Germany, Singapore and the Netherlands.

The app has a Wi-Fi test tool that will scan the network to which one is connected. If any weaknesses are detected, it will advise connecting via the VPN.

The test tool scores a network from A (secure) to F, which means the network is insecure and you should proceed with extra caution.

It also checks if the Wi-Fi network one is connected to is public or private, if it's encrypted, how many other devices share the connection, if the IP address and the location are exposed, and if others can monitor or sniff device details.

The VPN services are being offered by SurfEasy, a company that Opera bought last year.

The app collects anonymous data which Opera makes available to third parties.

SurfEasy chief Chris Houston said: "We have incorporated a Viking in the app. The Vikings didn't care about borders, and they sure weren't afraid of public Wi-Fi! And with the right tools, they stayed safe. The Opera VPN app can help unlock online borders and is the closest thing to a Viking shield today’s mobile users have for virtual self-protection."

The Android-based service supports English, Arabic, French, German, Indonesian, Japanese, Portuguese, Russian, Polish, and Spanish.