DARK File

What are DARK files and how to open them

Are you having problems opening a DARK file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your DARK files.

What is a DARK file?

A .DARK file is a Dark Compressed Data file.

Dark compressed data files store data compressed by the Dark archiver, a utility designed to reduce file size using a two-stage lossless compression process. The first stage transforms data blocks via the Burrows-Wheeler Transform, rearranging symbols to group similar characters together. The second stage applies "Distance Coding," which efficiently encodes repeated substrings by referencing earlier data within each block. Dark aims to provide similar compression ratios to tools like GRZip while being faster, and it is available for Windows and Linux.

These files are written by the Dark compressor (sometimes called "Dark or OpenDark," the latter being an open-source variant). Compression takes place in blocks; larger blocks typically yield better compression at the cost of more memory. The program requires roughly five times the block size in memory, occasionally six times for certain older builds. To read (decompress) the content, the Dark or OpenDark tool must be used.

Files begin with a magic signature to identify their format: ASCII characters exclaim mark then "dark" ("!dark") appear at offset zero.

How to open DARK files

Important: Different programs may use files with the DARK file extension for different purposes, so unless you are sure which format your DARK file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: October 2, 2026

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