Defragger vs O&O Defrag

Defragger is a graphical Linux tool for examining and defragmenting filesystems, with a map showing file, free-space, and metadata allocation. Its analysis identifies fragmentation and displays filesystem blocks in an adaptive map. The project supports online defragmentation of ext4 and offline defragmentation and compaction of FAT16 and FAT32. FAT12 and exFAT can be analyzed, but not modified. A command-line interface can list, analyze, defragment, and compact volumes. The interface and command-line program run without elevated privileges; operations that need them use a PolicyKit-authorized helper over D-Bus. The stated environment is Linux with Qt 6 and KDE Kirigami; privileged mode also requires systemd, PolicyKit, and an active graphical PolicyKit agent. For ext4, Defragger uses Linux filesystem ioctls directly rather than calling e4defrag or filefrag. The project labels the software alpha, recommends backing up important data, and says ext4 has received the most testing. FAT write support is newer, so it recommends beginning with disposable or fully backed-up volumes. The software is dual-licensed under MIT or Apache License 2.0.

O&O Defrag has no write-up on Specifiction yet; its figures are above.