This tool is absolutely indispensable for consideralby reducing the risk of your computer being infected with malware when surfing on untrusted websites. Just run your webbrowser in a sandbox. And, of course, it's also very useful for testing executable files and patches from unknown or questionable sources. Just run the exe in a so-called sandbox and afterwards delete all the data that's been written to the sandbox. Sandboxie might seem a bit alien to unexperienced users. But in fact, it's very easy to use. Once you understood the concept, you will find this software is an invaluable security guard for risky things on your computer.

This is a must have little application. It allows you to test executables to see how they behave, without allowing anything being modified outside the specified Sandboxie folder, everything is written to files in the sandbox.

You can run infected files without harm to your PC, or run installers and copy/move the files you want (ie, make it portable) to another folder.

Sandboxie is an indispensable tool for browsing safely and executing questionable files; so secure you can run a virus inside it without it affecting your PC. "The problem we have is that browsers are inherently insecure," says Kevin Johnson, CEO at IT security consulting firm Secure Ideas. For example, HTML5 [used by youtube] offers no secure sandboxing protection, such as what Flash can have in the Chrome browser, he notes." Yes, web browsers are the weakest link in online security next to close source routers with out of date firmware. Without a sandbox you can't browse 100% securely. There were security holes recently patched in Chromes own sandbox. With sandboxie, you can stick an untrustworthy sandbox inside an unbreakable sandbox and nobody can harm your computer! Sandboxie cant stop hackers from accessing your computers data, but it will stop them from making any changes or permanent infections. All you do is empty the sandbox and the infection is GONE. I wish there were more and better apps out there, but at the time of this post sandboxie takes the cake.

Lifetime licenses are offered again for home users! Old comment left here for reference.

As of October 9th 2013, the developer has changed Sandboxie from a purchase to a subscription model. You have to pay a recurring fee of currently €15 yearly. The regular registration (perpetual/lifetime license) is no longer offered for sale.

I understand the reasoning behind it – continued work on the project needs to be supported somehow – but I personally think a subscription model is the worst way to go about this, and significantly lowers the value of the product for paying customers. Why not charge a fee if people want to upgrade to major new versions? By all means, sell an "update subscription" that goes at €15 a year, so people have the choice. But remotely disabling a software that a customer has at one point paid for is just wrong and disrespectful. The customer's continued use of an old version that's no longer updated costs the developer nothing.

It seems a very crummy move to me, potentially inspired by Adobe, who have gotten a well-deserved and massive blow of criticism for doing the same thing to their entire product range (which I believe might yet spell their downfall after some 30 years as an industry leader).

I should add, though, that the free version of Sandboxie is very generous in its functionality. If the paid license expires, it will not break completely, but revert to the unlicensed version, lacking some handy features and displaying nag screens, but remaining functional. That's generous of the deveoper, and at least the price of the subscription is fair. Still, the new subscription model makes it hard for me to unconditionally recommend the application to friends.

Excellent program, can be used for free at reduced functionality. Recommended for those of us who browse sites we really shouldn't.