Viber (Free on Android and iOS)
Free calls, text and picture messaging. There’s no need to login in as it runs in the background. Other users must also have Viber installed. Great for international phone calls but expect the connection to drop on occasions.
1Password (Free for the basic version on Android and iOS)
Keep all your passwords, website logins, credit card and bank account details in one place. Encrypted and synced between all your devices and computers. The app is expensive so it’s aimed at savvy users who spend a lot of time online.
Whatsapp (Free on Android and iOS)
Free text and picture and video messaging. There’s no need to login in as it runs in the background. Other users must also have WhatsApp installed. I find more people use WhatsApp than Viber.
Dropbox (Free on Android and iOS)
Store all your files (videos, pictures, spreadsheets, etc.) safely in the cloud and access them from any device.
Shredder (Android $7.99 and iOS $4.99)
Play chess against Shredder. Chosen because of its clean and simple user interface with additional options for hardcore players.
Instant heart rate (Android and iOS $2.99)
Accurately take your heart rate and see the real-time PPG graph. Store your previous recordings. Sometimes difficult to measure if you have tough skin on your fingers.