TreeSize, WinDirStat, DaisyDisk, WizTree, Baobab Disk Usage Analyzer, GrandPerspective, KDirStat, SpaceMonger, WhatSize, Disk Inventory X, SequoiaView, DiskUsage, Diskitude, Grid Size File Manager, DiskSavvy, JDiskReport, Filelight, Xinorbis, HDGraph, FolderSizes, Disk Space Fan, Overdisk, xdiskusage, DiskWave, Space Radar, Directory Size Calculator, Total Directory Report, SquirrelDisk, TDP x-Ray, 1Tree Pro, DirGraph, SpaceObServer, GetFolderSize, Disk Space Visualizer, DiskMapper, PA Storage Monitor, Precious Disk, ClearDisk, Disk Space Pro, DiskTriage, StepTree, Disk Space Finder, UtilStudio Disk Space Finder, Diskvision are some alternatives to RidNacs.