Sandboxie was an all-time favourite when it comes to sandboxing program on Windows. It helps us separate suspicious and unknown executables from the actual OS environment, test it, and decide whether we should keep it. It also helps defend against malware. Years ago it offered trial only, but after being acquired by Sophos, a renowned British company who provides security software, they gave us a personal free version. Then yesterday, Sophos announced that Sandboxie is completely free now, and is preparing to go open sourced.
I am happy for sure, a solid security software joins the open source field. This will make many people happy, not having to pay for this valuable masterpiece. Although Windows already has Sandbox feature, I think Sandboxie still has its place.