Facebook Messenger now allows users to encrypt their messages to prevent anyone from snooping on their private chats.
The 'Secret Conversations' feature was first announced by the social media firm back in July but has taken several months to test and roll out.
The addition of end-to-end encryption means that no one - including the government - will be able to access the hidden messages.
The Facebook-owned WhatsApp messaging app now encrypts all messages by default, but Facebook Messenger users will have the choice of whether to use the feature or not.
The feature also includes a 'timer' option for every message within a thread. This allows the message to self-destruct in a similar way to messages in Snapchat.
Apple already uses end-to-end encryption in iMessage for years and Viber added the feature a few months ago.
The difference with Facebook is that it encrypts messages only when users decide to turn on secret conversations manually.
"It's table stakes in the industry now for messaging apps to offer this to people," Messenger product manager Tony Leach told Wired.
"We wanted to make sure we're doing what we can to make messaging private and secure."
In a post on its blog in July, a Facebook spokesperson wrote: "We are starting to test the ability to create one-to-one secret conversations in Messenger that will be end-to-end encrypted and which can only be read on one device of the person you’re communicating with.
"That means the messages are intended just for you and the other person — not anyone else, including us."
With 'end-to-end' encryption, messages are visible only to the person who has sent them and the individuals that were meant to receive.
The system works by using a ‘lock’ to secure messages between individuals or in a group chat.
This lock is paired with a distinct ‘key,’ which only the sender and the recipients will have.
This will lock out cyber criminals, hackers, "oppressive regimes", and even WhatsApp officials to keep your data private, the blog says.
The new feature follows harsh criticism after Facebook updated its internal search engine, letting users to browse the entire social network for the first time.
This meant that previously private profiles appeared on Google and all public posts suddenly became searchable.
Users are advised to regularly check their account to ensure anything they want to be kept private does not slip through the net, as the tech company often changes its security settings without warning.