CCleaner, Glary Utilities, BleachBit, Advanced SystemCare, PrivaZer, Clean Master, SD Maid SE, AVG PC TuneUp, Auslogics BoostSpeed, SDelete, Wise Disk Cleaner, Intego Washing Machine, Tron Script, TFC - Temp File Cleaner, Red Button, MAGIX PC Check & Tuning, Smart PC, WinExt Free, DiskMax, MRU-Blaster, MacFly Pro, RegToy, Amigabit Privacy Cleaner, ATF-Cleaner, Mz Ultimate Tweaker, Argente Utilities, WinASO Registry Optimizer, Mz Ultimate Cleaner, System Cleaner, UnCleaner, D-ClearSystem, Little Disk Cleaner, Perfect Utilities, TweakVista, Odkurzacz, Square Privacy Cleaner, Xleaner, Empty Temp Folders, Total Privacy, EzPcFix, MacTuneUp, PrivacyScan are some alternatives to System Ninja.