Facebook has said in the past that encrypting chat on the site could be difficult. However, users can achieve end-to-end encryption for their Facebook chats right now using an open source program called Cryptocat.

The program works by logging in to a user’s Facebook account and pulling their contact list to set up chats. If you open a chat with another user who is on Cryptocat, the conversation will remain hidden both from Facebook and from Cryptocat itself. Facebook will know that two users sharing an encrypted connection are chatting, but if they attempt to see the messages being exchanged they will simply see “[encrypted message].” However, as Cryptocat founder Nadim Kobeissi says, users should already expect that Facebook has that information.

“There’s no harm in Cryptocat using this already-given metadata to allow these users to set up encrypted chats,” he wrote. “The usability benefits of being able to quickly see which friends are online and ready for an encrypted chat remain overly substantial for those users.”

Users of Cryptocat can chat with people who aren’t using the program, though conversations will only be kept hidden when both users are on it.

The latest version of Cryptocat with encrypted chat is currently available for Chrome, Safari and Opera, and updates for Firefox are expected to be released by the end of the week.