This form creates unique passwords for websites that require a secure password, such as any site wanting personal information or a credit card number.

This form combines a single master password with a key unique to each website. Have one good master password that you can remember and use only for this purpose. For the site key, I recommend some version of the website name, following a rule that you can easily remember.

Save this form on a webpage that you can always reach. You can also email the html for this page as an attachment to a webmail account that you can access anywhere.

The javascript performs all calculations in your browser. None of the form information passes back to the webserver.

If someone learns your password for one site, they cannot easily derive the password for other sites. They would need to perform a dictionary attack against both the master password and site key, then guess keys for other sites.

Some people invent passwords for each site and save them in an encrypted file. That encrypted file then requires extraordinary security, unlike this javascript page.

I also recommend keeping a private list of those sites for which you use this system.