There are a number of software applications which claim to store your passwords securely - in an encrypted "safe". To use these you typically need to install the application on your PC or keep it on a USB stick (or in some cases use a cloud service), and remember a single master password which lets you into the "safe".
Some of these systems are sold by reputable companies, are well-regarded, and may meet your needs. The advantages of using STEN are ...
