Why Defraggler is safe to use
Windows has an internal API (Application Programming Interface) that third-party applications such as Defraggler can use to move and delete files. This API works the same way Windows does when it moves or deletes files, and is very safe. Even if the PC crashes or you experience a power failure during defragmentation, Windows can usually complete the file operations or cancel them without file corruption.
Defraggler uses the Windows API, and is a safe and effective choice for your defragging needs.