ncdu, TreeSize, WinDirStat, DaisyDisk, WizTree, SpaceSniffer, Baobab Disk Usage Analyzer, KDirStat, SpaceMonger, WhatSize, OmniDiskSweeper, Disk Inventory X, SequoiaView, DiskUsage, crossdirstat, Diskitude, Grid Size File Manager, DiskSavvy, JDiskReport, Filelight, Xinorbis, HDGraph, Space Gremlin, FolderSizes, Overdisk, xdiskusage, DiskWave, Space Radar, Directory Size Calculator, FilePro, TreePie, SquirrelDisk, K4DirStat, RidNacs, i.Disk, SupaView, TDP x-Ray, DirGraph, SpaceObServer, GetFolderSize, Disk Space Visualizer, DiskMapper, PA Storage Monitor, Disk Space Fan Pro, ClearDisk, diskring, DiskTriage, StepTree, Disk Health, GD Map, Disk Space Finder, Purple Tree, Eximo, UtilStudio Disk Space Finder, Diskvision are some alternatives to GrandPerspective.