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Rubyzip is a ruby library for reading and writing zip files.

Important note

The Rubyzip interface has changed!!! No need to do require "zip/zip" and Zip prefix in class names removed.

If you have issues with any third-party gems that require an old version of rubyzip, you can use this workaround:

gem 'rubyzip', '>= 1.0.0' # will load new rubyzip version
gem 'zip-zip' # will load compatibility for old rubyzip API.


  • Ruby 2.4 or greater (for rubyzip 2.0; use 1.x for older rubies)


Rubyzip is available on RubyGems:

gem install rubyzip

Or in your Gemfile:

gem 'rubyzip'


Basic zip archive creation

require 'rubygems'
require 'zip'

folder = "Users/me/Desktop/stuff_to_zip"
input_filenames = ['image.jpg', 'description.txt', 'stats.csv']

zipfile_name = "/Users/me/Desktop/", Zip::File::CREATE) do |zipfile|
  input_filenames.each do |filename|
    # Two arguments:
    # - The name of the file as it will appear in the archive
    # - The original file, including the path to find it
    zipfile.add(filename, File.join(folder, filename))
  zipfile.get_output_stream("myFile") { |f| f.write "myFile contains just this" }

Zipping a directory recursively

Copy from here

require 'zip'

# This is a simple example which uses rubyzip to
# recursively generate a zip file from the contents of
# a specified directory. The directory itself is not
# included in the archive, rather just its contents.
# Usage:
#   directory_to_zip = "/tmp/input"
#   output_file = "/tmp/"
#   zf =, output_file)
#   zf.write()
class ZipFileGenerator
  # Initialize with the directory to zip and the location of the output archive.
  def initialize(input_dir, output_file)
    @input_dir = input_dir
    @output_file = output_file

  # Zip the input directory.
  def write
    entries = Dir.entries(@input_dir) - %w[. ..], ::Zip::File::CREATE) do |zipfile|
      write_entries entries, '', zipfile


  # A helper method to make the recursion work.
  def write_entries(entries, path, zipfile)
    entries.each do |e|
      zipfile_path = path == '' ? e : File.join(path, e)
      disk_file_path = File.join(@input_dir, zipfile_path)

      if disk_file_path
        recursively_deflate_directory(disk_file_path, zipfile, zipfile_path)
        put_into_archive(disk_file_path, zipfile, zipfile_path)

  def recursively_deflate_directory(disk_file_path, zipfile, zipfile_path)
    zipfile.mkdir zipfile_path
    subdir = Dir.entries(disk_file_path) - %w[. ..]
    write_entries subdir, zipfile_path, zipfile

  def put_into_archive(disk_file_path, zipfile, zipfile_path)
    zipfile.add(zipfile_path, disk_file_path)

Save zip archive entries in sorted by name state

To save zip archives in sorted order like below, you need to set ::Zip.sort_entries to true


After this, entries in the zip archive will be saved in ordered state.

Default permissions of zip archives

On Posix file systems the default file permissions applied to a new archive are (0666 - umask), which mimics the behavior of standard tools such as touch.

On Windows the default file permissions are set to 0644 as suggested by the Ruby File documentation.

When modifying a zip archive the file permissions of the archive are preserved.

Reading a Zip file

MAX_SIZE = 1024**2 # 1MiB (but of course you can increase this)'') do |zip_file|
  # Handle entries one by one
  zip_file.each do |entry|
    puts "Extracting #{}"
    raise 'File too large when extracted' if entry.size > MAX_SIZE

    # Extract to file or directory based on name in the archive

    # Read into memory
    content =

  # Find specific entry
  entry = zip_file.glob('*.csv').first
  raise 'File too large when extracted' if entry.size > MAX_SIZE

Notice about ::Zip::InputStream

::Zip::InputStream usable for fast reading zip file content because it not read Central directory.

But there is one exception when it is not working - General Purpose Flag Bit 3.

If bit 3 (0x08) of the general-purpose flags field is set, then the CRC-32 and file sizes are not known when the header is written. The fields in the local header are filled with zero, and the CRC-32 and size are appended in a 12-byte structure (optionally preceded by a 4-byte signature) immediately after the compressed data

If ::Zip::InputStream finds such entry in the zip archive it will raise an exception.

Password Protection (Experimental)

Rubyzip supports reading/writing zip files with traditional zip encryption (a.k.a. "ZipCrypto"). AES encryption is not yet supported. It can be used with buffer streams, e.g.:

Zip::OutputStream.write_buffer(''),'password')) do |out|
  out.write my_data

This is an experimental feature and the interface for encryption may change in future versions.

Known issues

Modify docx file with rubyzip

Use write_buffer instead open. Thanks to @jondruse

buffer = Zip::OutputStream.write_buffer do |out|
  @zip_file.entries.each do |e|
    unless [DOCUMENT_FILE_PATH, RELS_FILE_PATH].include?(

  out.write xml_doc.to_xml(:indent => 0).gsub("\n","")

  out.write rels.to_xml(:indent => 0).gsub("\n","")
end, "wb") {|f| f.write(buffer.string) }


Existing Files

By default, rubyzip will not overwrite files if they already exist inside of the extracted path. To change this behavior, you may specify a configuration option like so:

Zip.on_exists_proc = true

If you're using rubyzip with rails, consider placing this snippet of code in an initializer file such as config/initializers/rubyzip.rb

Additionally, if you want to configure rubyzip to overwrite existing files while creating a .zip file, you can do so with the following:

Zip.continue_on_exists_proc = true

Non-ASCII Names

If you want to store non-english names and want to open them on Windows(pre 7) you need to set this option:

Zip.unicode_names = true

Sometimes file names inside zip contain non-ASCII characters. If you can assume which encoding was used for such names and want to be able to find such entries using find_entry then you can force assumed encoding like so:

Zip.force_entry_names_encoding = 'UTF-8'

Allowed encoding names are the same as accepted by String#force_encoding

Date Validation

Some zip files might have an invalid date format, which will raise a warning. You can hide this warning with the following setting:

Zip.warn_invalid_date = false

Size Validation

By default (in rubyzip >= 2.0), rubyzip's extract method checks that an entry's reported uncompressed size is not (significantly) smaller than its actual size. This is to help you protect your application against zip bombs. Before extracting an entry, you should check that its size is in the range you expect. For example, if your application supports processing up to 100 files at once, each up to 10MiB, your zip extraction code might look like:

MAX_FILE_SIZE = 10 * 1024**2 # 10MiB
MAX_FILES = 100'') do |zip_file|
  num_files = 0
  zip_file.each do |entry|
    num_files += 1 if entry.file?
    raise 'Too many extracted files' if num_files > MAX_FILES
    raise 'File too large when extracted' if entry.size > MAX_FILE_SIZE

If you need to extract zip files that report incorrect uncompressed sizes and you really trust them not too be too large, you can disable this setting with

Zip.validate_entry_sizes = false

Note that if you use the lower level Zip::InputStream interface, rubyzip does not check the entry sizes. In this case, the caller is responsible for making sure it does not read more data than expected from the input stream.

Compression level

When adding entries to a zip archive you can set the compression level to trade-off compressed size against compression speed. By default this is set to the same as the underlying Zlib library's default (Zlib::DEFAULT_COMPRESSION), which is somewhere in the middle.

You can configure the default compression level with:

Zip.default_compression = X

Where X is an integer between 0 and 9, inclusive. If this option is set to 0 (Zlib::NO_COMPRESSION) then entries will be stored in the zip archive uncompressed. A value of 1 (Zlib::BEST_SPEED) gives the fastest compression and 9 (Zlib::BEST_COMPRESSION) gives the smallest compressed file size.

This can also be set for each archive as an option to Zip::File:'', Zip::File::CREATE, {compression_level: 9}) do |zip|
  zip.add ...

Zip64 Support

By default, Zip64 support is disabled for writing. To enable it do this:

Zip.write_zip64_support = true

NOTE: If you will enable Zip64 writing then you will need zip extractor with Zip64 support to extract archive.

Block Form

You can set multiple settings at the same time by using a block:

  Zip.setup do |c|
    c.on_exists_proc = true
    c.continue_on_exists_proc = true
    c.unicode_names = true
    c.default_compression = Zlib::BEST_COMPRESSION


Rubyzip is known to run on a number of platforms and under a number of different Ruby versions. Please see the table below for what we think the current situation is. Note: an empty cell means "unknown", not "does not work".

OS 2.4 2.5 2.6 2.7 3.0 Head JRuby JRuby Head Truffleruby 21.1.0 Truffleruby Head
Ubuntu 20.04 CI CI CI CI CI ci CI ci CI ci
Mac OS 10.15.7 CI x x x x x x
Windows 10 x
Windows Server 2019 CI

Key: CI - tested in CI, should work; ci - tested in CI, might fail; x - known working; o - known failing.

Please raise a PR if you know Rubyzip works on a platform/Ruby combination not listed here, or raise an issue if you see a failure where we think it should work.


Install the dependencies:

bundle install

Run the tests with rake:


Please also run rubocop over your changes.

Our CI runs on GitHub Actions. Please note that rubocop is run as part of the CI configuration and will fail a build if errors are found.

Website and Project Home


See for a comprehensive list.

Current maintainers

  • Robert Haines (@hainesr)
  • John Lees-Miller (@jdleesmiller)
  • Oleksandr Simonov (@simonoff)

Original author

  • Thomas Sondergaard


Rubyzip is distributed under the same license as ruby. See