HDDEpxert is described as 'HDDExpert gives you a crystal-clear vision of your Hard Drive (HDD or SSD) health and performance and translates S.M.A.R.T. attributes into readable indication' and is an app in the OS & Utilities category. There are more than 25 alternatives to HDDEpxert for a variety of platforms, including Windows, Mac, Linux, BSD and MS-DOS. The best alternative is CrystalDiskInfo, which is both free and Open Source. Other great apps like HDDEpxert are GSmartControl (Free, Open Source), HD Tune (Freemium), Hard Disk Sentinel (Paid) and Victoria (Free).
CrystalDiskInfo is a HDD/SSD utility software which supports S.M.A.R.T. It shows the health status much more clearly than similar tools. The "Function / Graph" is especially interesting for the "Reallocated Sectors Count".
Victoria is a small application designed to assess performance, test and perform minor repairs to your IDE drive and SATA HDD. It's designed primarily for HDD repairmen in stationary conditions and is not intended to test the system hard drive.
The smartmontools package contains two utility programs (smartctl and smartd) to control and monitor storage systems using the Self-Monitoring, Analysis and Reporting Technology System (SMART) built into most modern ATA and SCSI harddisks.
HDDScan is a freeware utility for storage devices diagnostics (HDD, RAID, Flash). The program can scan storage device for bad blocks, show S.M.A.R.T. attributes and change some HDD parameters such as AAM, APM, etc.