Seedkeys от Willem

This is a simple password manager that allows you to generate a secure password for any site you visit by only remembering your "master password" (Seed). You can easily auto-fill passwords in forms around the web by entering your seed and letting this add-on convert it to your password.

Set-up

1. After installing this add-on, click on the icon that appears and fill in the Salt and Seed fields. You can use anything as value, but it is recommended to use an easy-to-type but hard-to-guess seed.
2. Take note of the values you just filled in, including capitals and differentiate between similar characters (such as the capital I and lowercase L). Store this information somewhere safe and secure where nobody can access it.
3. You're done setting up.

Usage

1. Make sure you have supplied a salt in this addon. You can check your salt by clicking the icon in your browser.
2. Go to any website, log in, and edit your password.
3. Fill in your seed (instead of your password)
4. While your cursor is still in the password field, hit CTRL+ALT+S or right-click and select the "Convert seed to password" option.
5. Your seed will be converted to your password.
6. Save your new password, log out of the website, and go to the log-in screen again
7. Again: Fill in your seed instead of your password, and hit CTRL+ALT+S or right-click and select the "Convert seed to password" option.
8. Done.

You can also test this process in a random text field on the web to see what happens. I highly recommend doing this first to have a little understanding in what happens.

How it works
The generator takes your seed, salt, and the entry (hostname of the site or a custom specified value), and hashes them to your password using an algorithm. You are free to go to http://seedkeys.com/ and download the index page to see how it works. Everything is rendered and generated client-side, so you can use this tool while in offline mode.

Disclaimer
I created this tool mainly for myself to have an easier time managing passwords on the web. You are free to use it, but I am in no way responsible for anything in any way. You are fully responsible for the security of your passwords, seed and salt. This product is free to use; if you paid for it, you were scammed!