archiving format, mainstream on Microsoft Windows systems; ZIP format
specifications are maintained by PKWare which
originally developed the
format as part of Phil Katz's compression utility PKZip (1989), and it
is currently undergoing evaluation for ISO/IEC standardization.
Newer archive formats like 7Z (7-Zip / p7zip), RAR (WinRar), and ACE
have gained popularity and
introduced several improvements (some of them later brought into ZIP
format) like better compression ratio, recovery records, strong
Anyway, ZIP format retained much of its popularity earned in several
years of widespread use due its ubiquitous support from many dedicated
software alternatives to WinZip, as well as basic built-in support in
most of modern operating
systems, being .zip file format specifications released in public
domain, which makes unzipping possible on almost all PC and devices.
is the default
archive format for PeaZip, being a good, fast general purpose archiving
format that can be handled by most archive managers - it is chosen as
default format by most other file archivers for the same reason.
algorithm used in PeaZip improves ZIP format performances on modern
multi core, multi threaded machines, and provides a slightly improved
compression over classic Deflate implementation retaining the full
compatibility with ZIP standard.
Zip format and variants
(JAR, CAB, IPA, APK,
ZIP compression is quite fast and
it's based on Deflate algorithm
in GZip format); alternatively Deflate64, BZip2, LZMA, and PPMd based
possible, and supported by PeaZip.
Recently WinZip (first GUI zip file utility on Microsoft Windows
platform, and still one of most popular "zipper" program) introduced
some new compression algorithms and a new
AES based encryption scheme, Advanced Encryption (AE-1, released in
2003, and AE-2 revision in 2004).
archives as well as classic
ZipCrypto-encrypted archives are supported by PeaZip, that is also
capable to read PKWare's AES encrypted zip archives, standard
introduced in 2003 with PKZip 6.0 Professional Edition.
Moreover many variants were built on zip format structure (Android APK,
Java JAR, Apple IPA, EPUB) or using Deflate compression (Microsoft CAB
and MS Office OPC "Open Packaging Conventions" and COMPOUND file types).
For some of these file types PeaZip does not allow editing archive
content (unless they are renamed as .zip files, and treated as plain
archives), only browsing and extraction, because file format
specifications involves maintaining special purpose meta-data fields
which are out of the scope of a general-purpose file archiver - those
files should be edited with specialized programs to correctly update
When is ZIP format
brief, .zip is a good choice anytime
it is important to keep the archive compatible with most archive
managers recipients may use, making it also an excellent choice for
content distribution. For same reson it is also
term archive / backup storage, as a such obiquitous format (with public
domain specifications) is unlike to be unsupported in any conceivable
Excellent. Deflate is light and fast for modern hardware, other
supported compression algorithms are more resource demanding.
Deflate is inferior to modern, more powerful (and power demanding)
compressors as 7Z or RAR. Modern ZIP software supports additional
algorithms to close the gap (BZip2, PPMd, LZMA) but archives may result
unreadable for older utilities.
Good. Recent format revisions provide efficent encryption standards.
recovery records option
available for RAR format.
PeaZip provides read/write support for .zip files, working as
extractor, opener (list, search and explore archived files and
directories), converter from/to Zip format, and integrity testing
ZIP is the default
archive format for PeaZip, which uses optimized 7-Zip/p7Zip Deflate
implementation to reduce zip file size while keeping compatibility with
other archival utilities.
The software can also manage password protected zip archives (encrypt
decrypt), and convert files to / from zip format.
As alternative, 7-Zip (on MS Windows systems) and p7zip (on Linux/BSD),
both free and Open Source tools, are recommended for working with zip
Compress to ZIP format
Use one of the following procedures to add
folders to a new or
into an existing .zip file
From main archive creation interface it is possible to apply encryption (recipient will need
to enter a password to read/extract the archive), and to split files - set creation
of multiple volumes declaring
the maximum output size
(spanned archive), in order to keep the output size
below mandatory limits (e.g. upload or mail attachment size).
Zip files from the system's file
Select files and folders and use
entry PeaZip, Add to archive: you will be prompted to archive creation
screen, allowing to set compression settings, output destination,
encryption (password protection), and other options.
From "Advanced" tab, you can
fine-tune compression settings: faster or higher compression level,
algorithm, solid compression
block size, compress open files, create self extracting archive (SFX)
will not need an archive
program to extract the data...
From "Console" and "Schedule" tab, the compression / backup task
created in the GUI can be saved as command line script and (on Microsoft
operating system) scheduled for execution at fixed time intervals
(hour, day of the week or of the month) - same apply for extraction /
restore tasks, as the same tabs are featured in archive extraction
Update existing ZIP archive
To update existing archive,
adding files and folders, proceed as shown above for archive creation,
but select an existing
archive as output and chose add (always
replace files in archive) or update (overwrite
only older files in archive) "archive function" in
Easiest way to edit an existing archive is opening it in PeaZip and
dragging files/folders to it, which will automatically activate update
mode - can be changed into add mode in advanced tab.
To remove (delete) data from
the archive, select items and press cancel or "Delete from archive"
button. Deleted items will not be recoverable from recycle bin.
Entries in the context menu on the right of delete button allows to
delete the entire archive in different supported ways (recycle, quick
delete, overwrite with zeroes, secure
delete shredding data to make the archive not recoverable)
Convert ZIP files
procedure using Convert button
extracts and then re-pack input archive files into any write-supported
format (7z, arc, pea, tar, zip...), optionally keeping or discarding
This makes possible to convert any type
supported for reading (e.g. ACE, CAB, RAR, TAR, ZIP...) into a new ZIP
file (either one for each individual input archive, or consolidating
all input items in a single output archive), as well as to convert
existing ZIP file into another write-supported format.
Open and extract ZIP file
Use one of the procedures described below to
(browse and search
inside the archive) and/or decompress
To extract a spanned (split) ZIP file, save all the parts in the same
directory, then open as usual the first volume of the archive, which
has Z01 or 001 extension - subsequent volumes have
progressively numbered file extensions (Z02, Z03 etc).
Unzip file from the system
archive's content, open it in
PeaZip with double click (if file extension is associated with the
application), or using system context menu "Open as archive" entry,
will attempt to read any user provided file type regardless file type
associations - this option is also available in PeaZip's context menu
Use context menu entry "Extract..."
extraction screen GUI where to set
output path and other options
Select one or more archives and use
entry Extract here or Extract
here (to new folder) for quick extraction with no further
Extract button shows full featured
extraction screen providing access to all options (password, set output
path, open output path after extraction, keep or delete original
archives, etc) and can send to extraction selected items only
Extract all to... button activate a
procedure only asking for output path
Simply drag & drop desired objects
application to the system
Doubleclick on an archived file to
mode, i.e. to inspect its content before considering the need for real
Manage encrypted ZIP archives
To create, or extract, an encrypted
.zip file, enter
the password in PeaZip clicking the padlock icon in the status bar
(in the file/archive browser) or below output address
field (in extraction or archiving interfaces), or click Tools >
password / keyfile in main menu, or press F9 accelerator key.
Supported algorithms for zip encryption, from Archive creation,
Advanced tab, are:
items inside the archive are marked by * sign.
AES256 (WinZip's Advanced Encryption
ZipCrypto, for legacy support only
Please note zip format
supports file-level encryption so multiple passwords can be used in the
same archive to encrypt different group of files - and consequently in
this case different password must be provided to access each part of
the archive, changing password entered in PeaZip.
"Keyfile" field is optional, leave it blank if you don't want to rely
factor authentication - keyfile is the "what you have" element (needs
to be handled safely), password (or passphrase) is the
non-material "what you know" element; both are needed for
recovering the encrypted file content.
Use of keyfile increases security over password
only encryption since also having access to the keyfile will be
required to perform the extraction, eliminating the need of overly
complex passwords to resist to social engineering profiling, and
brute-forcing or dictionary attacks.
External online resources: ZIP file
format on Wikipedia, PKWare PKZip, Deflate
free Zip software, what is .zip file extension wiki, how do
open zip files (handle compress / decompress, read / write, view
browse & search zip compressed data), edit existing zip archive,
zip to new folder, drag and drop extraction from zipped file.