The developers of the popular Firefox browser announced the imminent launch of an interesting new feature. It is reported that it will allow checking whether certain user accounts have been hacked.The new tool that Mozilla is developing compares user accounts with data from the database of the site Have I Been Pwned (HIBP), which stores a list of ever hacked accounts. It is reported that the innovation will appear in new versions of Firefox. It is known that the tool will be called Firefox Monitor. To use it, you must enter the email address of interest. If this account has been compromised, the tool will report what data has been stolen and provide a number of tips to improve the protection of user accounts. To try out the new tool in practice will be possible next week. However, we are talking about 250 thousand users, mostly located in the United States. If Firefox Monitor justifies the developers' hopes, it will become available to all users a bit later.