Is my password safe?
How Secure Is My Password uses JavaScript, which is a client side language - all the calculations are performed by your computer. This means that once you've loaded the site in your browser nothing else will pass between your computer and the server - nothing you type in leaves your computer. If you'd like to check this you can load the site and then turn off your internet connection - everything will continue to work.
Why doesn't the site use HTTPS?
You won't get a little padlock sign for this site, which means it's not using HTTPS - an encrypted form of HTTP. This is because no information is passed between your computer and the server, so there's nothing that needs encrypting.