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Ruby implementation for generating Tiny URL. The implementation is based on python-short_url.

A bit-shuffling approach is used to avoid generating consecutive, predictable URLs. However, the algorithm is deterministic and will guarantee that no collisions will occur.

The URL alphabet is fully customizable and may contain any number of characters.

The intended use is that incrementing, consecutive integers will be used as keys to generate the short URLs. For example, when creating a new URL, the unique integer ID assigned by a database could be used to generate the URL by using this module. Or a simple counter may be used. As long as the same integer is not used twice, the same short URL will not be generated twice.

More detail is here.


Add this line to your application's Gemfile:

gem 'ruby-short_url'

And then execute:

$ bundle

Or install it yourself as:

$ gem install ruby-short_url


# shorten id # => "00crI"

# decode encoded"00crI") # => 123456

Create your own URL Shortner

class CustomEncoder < Ruby::ShortUrl::Encoder
  def initialize
    # Set your own custom alphabet and block_size
    super(alphabet: "0123abc", block_size: 5)
# > custom_encoder =
# => #<CustomEncoder:0x007faf3babc830 @alphabet="0123abc", @block_size=5, @mask=31, @mapping=[0, 1, 2, 3, 4]>
# > custom_encoder.encode_url(1)
# => "00022"
# > custom_encoder.encode_url(2)
# => "00011"
# > custom_encoder.encode_url(3)
# => "00033"
# > custom_encoder.encode_url(4)
# => "0000a"
# > custom_encoder.decode_url("00022")
# => 1
# > custom_encoder.decode_url("00011")
# => 2
# > custom_encoder.decode_url("00033")
# => 3
# > custom_encoder.decode_url("0000a")
# => 4


After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install.


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.