UltraDefrag

{{Infobox software

| name = UltraDefrag

| logo = Ultra defrag.gif

| screenshot =

| caption = UltraDefrag 12 on Windows 10

| author = Dmitri Arkhangelski, Stefan Pendl, Justin Dearing, Sayem Chaklader

| developer = Green Gate Systems, LLC

| released = {{Start date and age|2007|07|05}}

| repo = {{URL|https://sourceforge.net/projects/ultradefrag/}} (Only open source release of UltraDefrag)

| operating system = Windows 11
Windows 10
Windows 8.1
Windows 8
Windows 7
Windows Vista
Windows XP
Windows 2000
Windows NT 4.0

| platform = IA-32, x64, IA-64

| programming language = C, C++, Lua, JavaScript

| genre = Defragmentation software

| license = Proprietary for 8.0.0+,
GNU GPL for 7.1.x and under

| website = {{URL|https://ultradefrag.net/}}

}}

UltraDefrag is a disk defragmentation utility for Microsoft Windows. Prior to version 8.0.0 it was released under the GNU General Public License. The only other Windows-based defragmentation utility licensed under the GNU GPL was JkDefrag, discontinued in 2008.{{cite web | url = http://www.kessels.nl/JkDefrag/index.html | title = JkDefrag v3.36 | first = Jeroen | last = Kessels | archiveurl = https://web.archive.org/web/20150215060146/http://kessels.nl/JkDefrag/index.html | archivedate = 2015-02-15 }}

In 2018, UltraDefrag sources have been relicensed to Green Gate Systems. Their enhanced version, released under a proprietary license, features automatic defragmentation, disk cleanup before defragmentation, graphical interface for setting user preferences, optimization of solid state drives, full compatibility with Windows 11 and 10, and is said to have much faster disk processing algorithms.{{cite web | url = https://sourceforge.net/p/ultradefrag/news/2018/09/ultradefrag-710-and-800-have-been-released/ | title = UltraDefrag 7.1.0 and 8.0.0 have been released}}

UltraDefrag uses the defragmentation part of Windows API and works on Windows NT 4.0 and later. It supports FAT12, FAT16, FAT32, exFAT, and NTFS file systems.{{cite web | url = https://ultradefrag.sourceforge.net/handbook/Introduction.html | title = UltraDefrag Handbook: Introduction}}

Jean-Pierre André, one of the developers of NTFS-3G, has created a fork of UltraDefrag 5 that runs on Linux. It only has a command-line interface.{{cite web |title=Advanced NTFS-3G Features |url=https://jp-andre.pagesperso-orange.fr/advanced-ntfs-3g.html#ultradefrag |website=jp-andre.pagesperso-orange.fr |accessdate=10 October 2019}}