Contig is a single-file defragmenter that attempts to make files contiguous on disk. Its perfect for quickly optimizing files that are continuously becoming fragmented, or that you want to ensure are in as few fragments as possible.
Contig can be used to defrag an existing file, or to create a new file of a specified size and name, optimizing its placement on disk. Contig uses standard Windows defragmentation APIs so it won't cause disk corruption, even if you terminate it while its running.
How it Works:
Contig uses the native Windows NT defragmentation support that was introduced with NT 4.0 (see my documentation of the defrag APIs for more information). It first scans the disk collecting the locations and sizes of free areas. Then it determines where the file in question is located. Next, Contig decides whether the file can be optimized, based on free areas and the number of fragments the file currently consists of. If the file can be optimized, it is moved into the free spaces of the disk.