6. Skype:
Skype was downloaded over 1.3 billion times & the only microsoft owned app which made it to the list.

   5. Snapchat:
Photo-messaging app Snapchat grabs the 5th spot with 1.5 billion downloads & the only app which is not owned by Facebook in the top five list.

   4. Instagram:
Photo and video sharing social media platform Instagram was downloaded 2.7 billion times over the decade. (Facebook bought instagram in 2012)

   3. Whatsapp: 
Encrypted messaging app whatsapp (bought by facebook in 2014) was downloaded 4.3 billion times in the last 10 years.

   2. Facebook Messenger:
Messaging Service owned by Facebook grabs the 2nd spot with 4.4 billion downloads over the decade.

   1. Facebook:
Inspite of many controversies & scandals, Facebook app tops the list with 4.6 billion downloads in last 10 years.

Here is the list of most downloaded apps of the decade: