Archive formats are used for backups, mobility, and archiving. Many archive formats compress the data to consume less storage space and result in quicker transfer times as the same data is represented by fewer bytes. Another benefit is that files are combined into one archive file which has less overhead for managing or transferring. There are numerous compression algorithms available to losslessly compress archived data; some algorithms are designed to work better (smaller archive or faster compression) with particular data types. Archive formats are used by most operating systems to package software for easier distribution and installation than binary executables.
RPM files consist of metadata concatenated with (usually) a cpio archive. Newer RPM systems also support other archives, as cpio is becoming obsolete. cpio is also used with initramfs.
A system for storing multiple files. LBR archives typically contained files processed by SQ, or the archive itself was compressed with SQ. LBR archives that were compressed with SQ ended with the extension .LQR
An archive format originally used mainly for archiving and distribution of the exact, nearly-exact, or custom-modified contents of an optical storage medium such as a CD-ROM or DVD-ROM. However, it can be used to archive the contents of other storage media, selected partitions, folders, and/or files. The resulting archive is typically optimized for convenient rendering to (re-)writable CD or DVD media.
.lbr
Commodore 64/128
A library format used primarily on the Commodore 64 and 128 lines of computers. This bears no resemblance to the DOS LBR format. While library files were quick to implement (a number of programs exist to work with them) they are crippled in that they cannot grow with use: once a file has been created it cannot be amended (files added, changed or deleted) without recreating the entire file.
A common archive format used on Unix-like systems. Generally used in conjunction with compressors such as gzip, bzip2, compress or xz to create .tar.gz, .tar.bz2, .tar.Z or tar.xz files.
Brotli is a compression algorithm developed by Google for textual web content, and typically achieves higher compression ratios than other algorithms for this use case.
A compression format developed by Google, and open-sourced in 2011. Snappy aims for very high speeds, reasonable compression, and maximum stability rather than maximum compression or compatibility with any other compression library. It is an LZ77 derivative, without entropy encoding.
Squeeze: A program which compressed files using Huffman coding. A file which was "squeezed" had the middle initial of the name changed to "Q", so that a squeezed text file would end with .TQT, a squeezed executable would end with .CQM or .EQE. Typically used with .LBR archives, either by storing the squeezed files in the archive, or by storing the files decompressed and then compressing the archive, which would have a name ending in ".LQR".
A compression program written by Steven Greenberg implementing the LZW algorithm. For several years in the CP/M world when no implementation was available of ARC, CRUNCHed files stored in .LBR archives were very popular. CRUNCH's implementation of LZW had a somewhat unusual feature of modifying and occasionally clearing the code table in memory when it became full, resulting in a few percent better compression on many files.
A compression format using LZMA2 to yield high compression ratios. The LZMA algorithm is an LZ77 derivative, with entropy encoding in the form of range encoding.
Compression format(s) used by some DOS and Windows install programs. MS-DOS includes expand.exe to decompress its install files. The compressed files are created with a matching compress.exe command. The compression algorithm is LZSS.
macOS, restoration on different platforms is possible although not immediate
Yes
Based on 7z. Preserves Spotlight metadata, resource forks, owner/group information, dates and other data which would be otherwise lost with compression.
Made obsolete by the introduction of AppleDouble-encoded 7z archives (Macintosh only).
A format that compresses and doubly encrypt the data (AES256 and CAS256) avoiding brute force attacks, also hide files in an AFA file. It has two ways to safeguard data integrity and subsequent repair of the file if has an error (repair with AstroA2P (online) or Astrotite (offline)).
Created by Yaakov Gringeler; released last in 2003 (Compressia 1.0.0.1 beta), now apparently defunct. Free trial of 30 days lets user create and extract archives; after that it is possible to extract, but not to create.
Supports "Internet-enabled" disk images, which, once downloaded, are automatically decompressed, mounted, have the contents extracted, and thrown away. Currently, Safari is the only browser that supports this form of extraction; however, the images can be manually extracted as well. This format can also be password-protected or encrypted with 128-bit or 256-bit AES encryption.
Open source archiver supporting authenticated encryption, cascaded encryption, volume spanning, customizable object level and volume level integrity checks (form CRCs to SHA-512 and Whirlpool hashes), fast deflate based compression
A package format to enable distribution of applications and libraries by bundling many PHP code files and other resources (e.g. images, stylesheets, etc.) into a single archive file
The format from the PIM - a freeware compression tool by Ilia Muraviev. It uses an LZP-based compression algorithm with set of filters for executable, image and audio files.
The format from a proprietary archiving package. Odd among proprietary packages in that they focus on incorporating experimental algorithms with the highest possible compression (at the expense of speed and memory), such as PAQ, PPMD and PPMZ (PPMD with unlimited-length strings), as well as a proprietary algorithms.
.sda
Self Dissolving ARChive
Commodore 64, Commodore 128
Commodore 64, Commodore 128
Yes
SDAs refer to Self Dissolving ARC files, and are based on the Commodore 64 and Commodore 128 versions of ARC, originally written by Chris Smeets. While the files share the same extension, they are not compatible between platforms. That is, an SDA created on a Commodore 64 but run on a Commodore 128 in Commodore 128 mode will crash the machine, and vice versa. The intended successor to SDA is SFX.
A pre-Mac OS X Self-Extracting Archive format. StuffIt, Compact Pro, Disk Doubler and others could create .sea files, though the StuffIt versions were the most common.
.sen
Scifer
Multiple
Multiple
Yes
Scifer Archive with internal header
.sfx
Self Extracting Archive
Commodore 64, Commodore 128
Commodore 64, Commodore 128
Yes
SFX is a Self Extracting Archive which uses the LHArc compression algorithm. It was originally developed by Chris Smeets on the Commodore platform, and runs primarily using the CS-DOS extension for the Commodore 128. Unlike its predecessor SDA, SFX files will run on both the Commodore 64 and Commodore 128 regardless of which machine they were created on.
An archive format designed for the Apple II series of computers. The canonical implementation is ShrinkIt, which can operate on disk images as well as files. Preferred compression algorithm is a combination of RLE and 12-bit LZW. Archives can be manipulated with the command-line NuLib tool, or the Windows-based CiderPress.
The replacement for the .sit format that supports more compression methods, UNIX file permissions, long file names, very large files, more encryption options, data specific compressors (JPEG, Zip, PDF, 24-bit image, MP3). The free StuffIt Expander is available for Windows and OS X.
The "tarball" format combines tar archives with a file-based compression scheme (usually gzip). Commonly used for source and binary distribution on Unix-like platforms, widely available elsewhere. Xarchiver supports the .tar.zst Archive/Compression format on Unix-like platforms.
UltraCompressor 2.3 was developed to act as an alternative to the then popular PKZIP application. The main feature of the application is its ability to create large archives. This means that compressed archives with the UC2 file extension can hold almost 1 million files.
Based on PAQ, RZM, CSC, CCM, and 7zip. The format consists of a PAQ, RZM, CSC, or CCM compressed file and a manifest with compression settings stored in a 7z archive.
Native format of the Open Source KiriKiriVisual Novel engine. Uses combination of block splitting and zlib compression. The filenames and pathes are stored in UTF-16 format. For integrity check, the Adler-32 hashsum is used. For many proprietary games, the files are encrypted (and decoded on runtime) via so-called "cxdec" module, which implements xor-based encryption.
Yamazaki zipper archive. Compression format used in DeepFreezer archiver utility created by Yamazaki Satoshi.[18] Read and write support exists in TUGZip, IZArc and ZipZag
Journaling (append-only) archive format with rollback capability. Supports deduplication and incremental update based on last-modified dates. Multi-threaded. Compresses in LZ77, BWT, and context mixing formats. Open source.
File format used in conjunction with any archive format to provide error correction and file recovery, most often in newsgroup distribution of binary files.
File format used with WinRAR rar volumes. The data recovery is error correction data which is provided in the form of open recovery records and/or recovery volumes, allowing reconstruction of good archives (including reconstruction of entirely volumes)
^ abcdFile extensions may differ across platforms. The case of these extensions may differ on case-insensitive platforms.
^ abcdMIME media types may be conjectural. Very few have been officially registered with the IANA. Compression-only formats should often be denoted by the media type of the decompressed data, with a content coding indicating the compression format.
^ abcdCreation platform indicates the platform(s) under which a format can be created.
^If attaching .F to the file name is not possible with the DOS operating system, the second and third character of the filename extension are replaced by XF.
^Restoration platform indicates the platform(s) under which a format can be restored/extracted. Most file formats can be understood by more than one platform.
^"Restorable with free software" indicates whether the format can be restored using an extraction tool that is free software.
^RARLAB UnRAR is proprietary. The free unar has partial unpacking support for RAR1.3, RAR1.5, RAR2, RAR3 & RAR5 [13] and the free libarchive has partial unpacking support for RAR3[14] & RAR5[15].
^The DOS and Windows operating systems required filenames to include an extension (of at least one, and typically 3 characters) to identify the file type. Such extensions must be unique for each type of file. Many operating systems identify a file's type from its contents without the need for an extension in its name. However, the use of three-character extensions has been embraced as a useful and efficient shorthand for identifying file types.
^Archive files are often stored on magnetic or other media subject to storage errors. Many archive formats contain extra error detection or correction information which can be used by the software used to read the archive files to detect and possibly correct errors.
^Many archive formats contain redundant data embedded in the files in order to detect data storage or transmission errors, and the software used to read the archive files contains logic to detect and correct errors.
^Many archive formats include the capability to encrypt contents to prevent unauthorised access, using one of many available encryption methods.
^ While the original tar format uses the ASCII character encoding, current implementations use the UTF-8 (Unicode) encoding, which is backwards compatible with ASCII.
^ The PAQ family (with its lighter weight derivative LPAQ) went through many revisions, each revision suggested its own extension. For example: ".paq9a".
^ From 3.20 release RAR can store modification, creation and last access time with the precision up to 0.0000001 second (0.1 μs).[24][25]
^ WIM can store the ciphertext of encrypted files on an NTFS volume, but such files can only by decrypted if an administrator extracts the file to an NTFS volume, and the decryption key is available (typically from the file's original owner on the same Windows installation). Microsoft has also distributed some download versions of the Windows operating system as encrypted WIM files, but via an external encryption process and not a feature of WIM.
^ Not to be confused with the archiver JAR written by Robert K. Jung, which produces ".j" files.
^ abcde Compression is not a built-in feature of the formats, however, the resulting archive can be compressed with any algorithm of choice. Several implementations include functionality to do this automatically
^ Per-file compression with gzip, bzip2, lzo, xz, lzma (as opposed to compressing the whole archive). An individual can choose not to compress already compressed filenames based on their suffix as well.
^ abcd Most implementations can optionally produce a self-extracting executable
