GtkSort is a multiprocessor external disk sorter and data manipulator for systems that support GTK+. Its source code has been ported and tested to produce valid results in Linux/x86, Linux/amd64, Linux/alpha, HP-UX/hp-pa 11.11i, Tru64 5.1B, Solaris 10/x86 and Win32 NT Class operating systems.

GtkSort processes files using multi threading in order to implement parallel algorithms. It overlaps disk I/O with sorting and reduces I/O waits. By using only sequential files it utilizes the most of the disk's I/O bandwidth. By giving exclusive read or write permissions for each processed file to only one thread, it minimizes the conflicting I/O requests that reduce the hard disk's efficiency. In order to sort records, and depending on the data type of the sort keys, GtkSort uses the standard library quick sort or its own implementation of Most Significant Byte (MSB) radix sort. GtkSort uses cache efficient algorithms keeping the cache misses at a very low rate (0.4% in version 0.2.0).

GtkSort integrates a Graphical User Interface (GUI) based on GTK+ in order to increase its friendliness against the end user. It also integrates a Command Line Interface (CLI) so it can be used in shell scripts.

GtkSort is free and open source software distributed under the terms of the GNU Public License version 2.