Sandboxie Plus (formerly Sandboxie) is an open-source OS-level virtualization solution for Microsoft Windows. It started out as a sandboxing solution that creates an isolated operating environment in which applications can run without permanently modifying the local system. This virtual environment allows for controlled testing of untrusted programs and web surfing. Sandboxie Plus enhances the original Sandboxie by adding multiple sandboxes, per-sandbox snapshots, and full OS-level virtualization.