FacebookInc. is testing end-to-end encryption for its Facebook Messengerapp.

The company said in a July 8 release that users have beenasking for more safeguards. Private messages, called "secretconversations," through the new feature can be seen only by the sender andreceiver, barring even Facebook from accessing it. Users can also set thelength of time a message is visible, similar to 's messaging feature.

The feature is optional.

Messenger boasts more than 900 million monthly active users,according to an April post byFacebook's Vice President of Products David Marcus.

The announcement comes two months after , a Facebook subsidiarywith a more global user base, announced asimilar messaging safeguard.